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Can the ESA address the threats of atmospheric nitrogen deposition? insights from the case of the Bay Checkerspot Butterfly

Authors:

Abstract

The Bay Checkerspot Butterfly reached its threatened status largely as a result of habitat loss through development. The species now benefits from the habitat pro-tection powers of the Endangered Species Act, yet the biggest new hazard to the survival of remaining Bay Checkerspot Butterfly populations may come from atmos-pheric nitrogen deposition. Driven by combustion and agricultural emissions, such deposition is an important cause of change in ecosystem structure and function, including potentially critical changes in the remaining Bay Checkerspot Butterfly habitat. We use the Bay Checkerspot Butterfly case to examine whether the Endan-gered Species Act, as it currently stands, is capable of protecting endangered species from the newly appreciated, remote-origin threat of nitrogen deposition. We employ legal analysis that builds on relevant case law to determine whether the limitations on harmful activities as set by sections 7 and 9 of the Endangered Species Act can be applied to the emissions that cause nitrogen deposition. As part of the analysis, we juxtapose our case with a similar case that has become quite salient in recent discus-sions of conservation law: the case for using the Endangered Species Act to help control greenhouse gas emissions. Our findings leave us cautiously optimistic that the take and jeopardy prohibi-tions of the Endangered Species Act could be fruitfully leveraged against existing federal and state air quality and emission control programs to help improve the protection of nitrogen-sensitive species and ecosystems.
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CAN THE ESA ADDRESS THE THREATS
OF ATMOSPHERIC NITROGEN DEPOSITION?
INSIGHTS FROM THE CASE OF THE
BAY CHECKERSPOT BUTTERFLY
Zdravka Tzankova*
Dena Vallano**
Erika Zavaleta***
The Bay Checkerspot Butterfly reached its threatened status largely as a result
of habitat loss through development. The species now benefits from the habitat pro-
tection powers of the Endangered Species Act, yet the biggest new hazard to the
survival of remaining Bay Checkerspot Butterfly populations may come from atmos-
pheric nitrogen deposition. Driven by combustion and agricultural emissions, such
deposition is an important cause of change in ecosystem structure and function,
including potentially critical changes in the remaining Bay Checkerspot Butterfly
habitat. We use the Bay Checkerspot Butterfly case to examine whether the Endan-
gered Species Act, as it currently stands, is capable of protecting endangered species
from the newly appreciated, remote-origin threat of nitrogen deposition. We employ
legal analysis that builds on relevant case law to determine whether the limitations
on harmful activities as set by sections 7 and 9 of the Endangered Species Act can be
applied to the emissions that cause nitrogen deposition. As part of the analysis, we
juxtapose our case with a similar case that has become quite salient in recent discus-
sions of conservation law: the case for using the Endangered Species Act to help
control greenhouse gas emissions.
Our findings leave us cautiously optimistic that the take and jeopardy prohibi-
tions of the Endangered Species Act could be fruitfully leveraged against existing
federal and state air quality and emission control programs to help improve the
protection of nitrogen-sensitive species and ecosystems.
I. Introduction ............................................... 434
R
II. Nitrogen Deposition and Its Impacts on the Threatened
Checkerspot ............................................... 439
R
A. Ecological Impacts of Nitrogen Deposition .............. 439
R
B. The Impacts of Nitrogen Deposition on Bay Area
Serpentine Grasslands and Their Threatened Checkerspot
Inhabitants ............................................ 440
R
C. Sources of Nitrogen Deposition on Bay Area Serpentine
Grasslands ............................................ 441
R
III. The Endangered Species Act: A Brief Overview .............. 443
R
IV. Nitrogen Deposition as a Prohibited Take of Checkerspots? ... 445
R
* Assistant Professor, Department of Environmental Studies, University of California,
Santa Cruz.
** Post-doctoral Researcher, Department of Environmental Studies, University of Califor-
nia, Santa Cruz.
*** Assistant Professor, Department of Environmental Studies, University of California,
Santa Cruz.
The authors would like to thank Sarah Carvill and Peter Brewitt for helpful comments on
earlier drafts, and for their excellent research and editorial assistance. We are especially thank-
ful to Stuart Weiss, whose research on and dedication to the conservation of California serpen-
tine grasslands has both enabled and inspired our work. This research was supported by a
grant from the Kearney Foundation.
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434 Harvard Environmental Law Review [Vol. 35
A. “Harm” and “Take” Under the Current ESA Regime ..... 447
R
B. Habitat Modification as a Source of Harm to Protected
Wildlife ............................................... 449
R
C. Situating Nitrogen Deposition in the Uncertain Legal
Terrain of Take via Habitat Modification ................ 453
R
D. GHGs, Climate Change, and Polar Bears v. Nitrogen
Emissions, Nitrogen Deposition, and Checkerspots ....... 456
R
V. The Section 7 Jeopardy and Critical Habitat Standards and
EPA Regulation of Nitrogen Emissions Under the CAA ....... 462
R
A. Section 7 Requirements, Nitrogen Emissions, and Nitrogen
Deposition ............................................ 464
R
B. Section 7 Consultation for EPA Regulations of Nitrogen
Emissions Under the CAA .............................. 466
R
C. Section 7 Consultation for Permitting New Sources of
Nitrogen Emissions .................................... 467
R
D. EPA’s NAAQS for NO
2
................................. 468
R
E. SIPs and the Control of Nitrogen Impacts on Listed
Species................................................ 470
R
VI. The Pros and Cons of Leveraging the ESA as a Tool for
Reducing Ecologically Harmful Nitrogen Emissions .......... 472
R
I. I
NTRODUCTION
In many ways, the Bay Checkerspot Butterfly (“checkerspot”) is a per-
fect illustration of both the accomplishments and the shortfalls of federal
species protection. The checkerspot, the species behind Paul Ehrlich’s devel-
opment of the metapopulation concept,
1
was listed as threatened in 1987.
2
Like many other species, its initial decline was attributed to habitat degrada-
tion and loss caused by grazing and development in the increasingly popu-
lous San Francisco Bay Area.
3
While the Endangered Species Act (“ESA”
or “the Act”) has secured important protections for the checkerspot, helping
1
See, e.g., O
N THE
W
INGS OF
C
HECKERSPOTS
: A M
ODEL
S
YSTEM FOR
P
OPULATION
B
IOL-
OGY
(Paul R. Ehrlich & Ilkka Hanski eds., 2004); Paul R. Ehrlich & Dennis D. Murphy,
Conservation Lessons from Long-Term Studies of Checkerspot Butterflies, 1 C
ONSERVATION
B
IOLOGY
122 (1987); Susan Harrison et al., Distribution of the Bay Checkerspot Butterfly,
Euphydryas editha bayensis: Evidence for a Metapopulation Model, 132 T
HE
A
MERICAN
N
AT-
URALIST
360 (1988). A metapopulation dynamic means that a group of spatially distinct popu-
lations occasionally exchange individuals and can occupy sites that vary from year to year.
U.S. F
ISH
& W
ILDLIFE
S
ERV
., B
AY
C
HECKERSPOT
B
UTTERFLY
, 5-Y
EAR
R
EVIEW
: S
UMMARY
AND
E
VALUATION
2 (2009). Thus, presently unoccupied sites can still be part of the checker-
spot habitat. See id.
2
Determination of Threatened Status for the Bay Checkerspot Butterfly, 52 Fed. Reg.
35,366, 35,366 (Sept. 18, 1987) (codified at 50 C.F.R. pt. 17); See also U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 3.
R
3
See U.S. F
ISH
& W
ILDLIFE
S
ERV
., R
ECOVERY
P
LAN FOR
S
ERPENTINE
S
OIL
S
PECIES OF
THE
S
AN
F
RANCISCO
B
AY
A
REA
II-18991 (1998); Dennis D. Murphy & Stuart B. Weiss,
Ecological Studies and the Conservation of the Bay Checkerspot Butterfly, Euphydryas editha
bayensis, 46 B
IOLOGICAL
C
ONSERVATION
183, 18892 (1988).
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2011] Tzankova et al., Nitrogen Deposition 435
to shield it against some of the threats of habitat loss and habitat degrada-
tion,
4
a growing body of ecological knowledge points to a different factor
atmospheric nitrogen deposition as a likely major cause of ongoing
habitat degradation and of the species’ continued struggle.
5
Atmospheric ni-
trogen, and most importantly, emission-source nitrogen, is depositing on the
checkerspot’s serpentine grassland habitat and enabling the invasion of this
habitat by non-native grasses; the nitrogen-assisted non-natives are displac-
ing native serpentine plants, including the native forb plants on which the
habitat-restricted checkerspot depends for food and for successful comple-
tion of its reproductive cycle.
6
The question that logically emerges in this
context is whether the ESA is capable of protecting the checkerspot and its
serpentine grassland habitat from the newly identified threat of anthropo-
genic nitrogen emissions and nitrogen deposition.
A look across the terrestrial and aquatic ecosystems of the United States
suggests that the checkerspot is far from the only imperiled species suffering
from the negative effects of increasing nitrogen deposition.
7
The damaging
effects of high nitrogen loading can be seen in numerous ecosystems,
8
and
nitrogen deposition is often associated with “considerable declines in bi-
odiversity and loss of rare or protected species” on both local and regional
4
See, e.g., U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 17; see also Saving the Bay
R
Checkerspot Butterfly, C
TR
.
FOR
B
IOLOGICAL
D
IVERSITY
, http://www.biologicaldiversity.org/
species/invertebrates/Bay_checkerspot_butterfly/ (last visited Mar. 27, 2011).
5
See Michael J. Bean, Overcoming Unintended Consequences of Endangered Species
Regulation, 38 I
DAHO
L. R
EV
. 409, 410 (2002); S
TUART
B. W
EISS
, I
MPACTS OF
N
ITROGEN
D
EPOSITION ON
C
ALIFORNIA
E
COSYSTEMS AND
B
IODIVERSITY
(2006) [hereinafter W
EISS
, I
M-
PACTS OF
N
ITROGEN
D
EPOSITION
]; Stuart B. Weiss, Cars, Cows, and Checkerspot Butterflies:
Nitrogen Deposition and Management of Nutrient-Poor Grasslands for a Threatened Species,
13 C
ONSERVATION
B
IOLOGY
1476 (1999) [hereinafter Weiss, Cars, Cows, and Checkerspot
Butterflies].
6
U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 1415; U.S. F
ISH
& W
ILDLIFE
S
ERV
.,
R
supra note 3, at II-195; Susan Harrison & Joshua H. Viers, Serpentine Grasslands, in C
ALIFOR-
R
NIA GRASSLANDS
: E
COLOGY AND
M
ANAGEMENT
145, 15354 (Mark R. Stromberg et al., eds.,
2007); Laura F. Huenneke et al., Effects of Soil Resources on Plant Invasion and Community
Structure in Californian Serpentine Grassland, 71 E
COLOGY
478, at 478, 48889 (1990);
W
EISS
, I
MPACTS OF
N
ITROGEN
D
EPOSITION
,supra note 5; Weiss, Cars, Cows, and Checkerspot
R
Butterflies, supra note 5; see also Dennis D. Murphy et al., Introducing Checkerspots: Taxon-
R
omy and Ecology, in O
N THE
W
INGS OF
C
HECKERSPOTS
: A M
ODEL
S
YSTEM FOR
P
OPULATION
B
IOLOGY
,supra note 1, at 26; Murphy & Weiss, supra note 3, at 197.
R
7
See Mark E. Fenn et al., Ecological Effects of Nitrogen Deposition in the Western United
States, 53 B
IO
S
CIENCE
404, at 405, 417 (2003) [hereinafter Fenn et al., Ecological Effects];
Mark E. Fenn et al., Nitrogen Excess in North American Ecosystems: Predisposing Factors,
Ecosystem Responses, and Management Strategies, 8 E
COLOGICAL
A
PPLICATIONS
706, at 706,
721 (1998); Gareth K. Phoenix et al., Atmospheric Nitrogen Deposition in World Biodiversity
Hotspots: The Need for a Greater Global Perspective in Assessing N Deposition Impacts, 12
G
LOBAL
C
HANGE
B
IOLOGY
470, at 471 (2006).
8
It can be seen in particular in those ecosystems exposed to high rates of atmospheric
nitrogen deposition for several decades. See, e.g., Roland Bobbink et al., The Effects of Air-
Borne Nitrogen Pollutants on Species Diversity in Natural and Semi-Natural European Vege-
tation, 86 J. E
COLOGY
717, 731 (1998) [hereinafter Bobbink et al., Air-Borne Nitrogen Pollu-
tants]; Roland Bobbink & Leon P. M. Lamers, Effects of Increased Nitrogen Deposition, in
A
IR
P
OLLUTION AND
P
LANT
L
IFE
20105 (J.N.B. Bell & Michael Treshow, eds., 2002).
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436 Harvard Environmental Law Review [Vol. 35
scales.
9
While the precise consequences of nitrogen deposition have yet to
be rigorously quantified, nitrogen deposition is projected as one of the great-
est drivers of global biodiversity loss over the coming century, along with
land use change and climate change.
10
And much like GHG-induced climate
change, nitrogen deposition presents a remote, emissions-related cause of
ecological disruption that threatens imperiled species and their remaining
habitats.
This Article uses the checkerspot as a case study for a broader examina-
tion of whether the ESA, as it currently stands, can help protect listed spe-
cies from the somewhat indirect, yet increasingly significant threat of
atmospheric nitrogen deposition. The case of the checkerspot presents a val-
uable opportunity to analyze both the limits and potential of the ESA to deal
with nitrogen deposition: the detrimental effects of such deposition were an
important element in a recent U.S. Fish and Wildlife Service (“FWS”) pro-
posal to change the checkerspot’s status from “threatened” to “endan-
gered.”
11
This proposed reclassification, which identifies impacts from
nitrogen deposition as the most significant current threat to the checkerspot,
raises two questions: (1) whether the nitrogen emissions responsible for such
deposition can be considered taking of listed wildlife in violation of section
9 of the ESA, and (2) if so, who should be held responsible for such taking.
It also puts a spotlight on federal actions that cause, regulate, or authorize
nitrogen emissions, because section 7 of the Act requires federal agencies to
ensure that none of their actions jeopardize the continued existence of listed
species or degrade their critical habitat.
12
We raise these questions with full awareness that there are numerous
causes of listed species decline such as edge effects or the disruption of
9
Phoenix et al., supra note 7, at 471; see also Roland Bobbink et al., Global Assessment
R
of Nitrogen Deposition Effects on Terrestrial Plant Diversity: A Synthesis, 20 E
COLOGICAL
A
PPLICATIONS
30, 41, 43, 51 (2010) [hereinafter Bobbink et al., Global Assessment]. The
population of the threatened desert tortoise of the southwestern U.S. deserts has declined due
to grazing pressure, habitat destruction, drought, disease, and a declining food base. Invasive
grasses able to utilize additional nitrogen from deposition now outcompete native forbs, reduc-
ing the nutritional quality of vegetation available to the tortoise. See Kenneth A. Nagy, Brian
T. Henen, & Devesh B. Vyas, Nutritional Quality of Native and Introduced Food Plants of
Wild Desert Tortoises, 32 J. H
ERPETOLOGY
260, 26264 (1998).
10
Johan Rockstr¨om et al., A Safe Operating Space for Humanity, 461 N
ATURE
472, 472
(2009); Osvaldo E. Sala et al., Global Biodiversity Scenarios for the Year 2100, 287 S
CIENCE
1770, 1770 (2000).
11
U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 1415, 31.
R
12
16 U.S.C. § 1536 (2006). The checkerspot case is further compelling as a context for
examining the ability of the ESA to offer protections against nitrogen deposition because the
mechanisms of nitrogen impact on the checkerspot and the causal chain that links nitrogen
emissions to the harmful impacts on remaining checkerspot populations are likely more
complex than those encountered in many other cases of nitrogen deposition damage to habitats
or species. Consequently, if it can be shown that ESA protections, specifically those in section
7 and section 9, extend to the checkerspot with regard to emission-source nitrogen deposition,
then the case for using the ESA to address nitrogen deposition harms on other listed species
could be stronger.
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2011] Tzankova et al., Nitrogen Deposition 437
fire cycles that remain largely beyond the reach of the ESA.
13
We also
acknowledge that extending existing statutes and regulations too far beyond
their normal scope could prove ineffective or even counterproductive.
14
Nonetheless, we work in a world where newly understood disturbance mech-
anisms can threaten the past achievements of species and habitat protection,
and where creating dedicated new policies to address each new disturbance
is often impractical, politically difficult, or both. We therefore believe it is
worth exploring the species and habitat protection versatility of well-estab-
lished and highly successful legal and regulatory tools such as the ESA. It is
especially important to examine their potential capacity to deal with new or
newly recognized threats.
Our interest in the capacity of the ESA to help deal with the significant
and pervasive issue of nitrogen emissions and nitrogen deposition has been
further strengthened by recent legal discussions on the potential for (and
appropriateness of) using the ESA to force reductions in GHG emissions,
given the impacts of GHG-driven climate change on a growing number of
federally listed species.
15
In the course of our analysis, we engage these
discussions, examining key similarities and differences between the ESA
case against GHG emissions and climate change on the one hand, and the
ESA case against nitrogen emissions and nitrogen deposition on the other.
Part II summarizes current knowledge of the ways that nitrogen deposi-
tion affects habitats and species, with particular emphasis on remaining
checkerspot populations and their serpentine grassland habitat. It also in-
troduces the principal anthropogenic sources of nitrogen deposition on
checkerspot habitat. Part III provides a brief overview of the ESA. Part IV
addresses the first of two key questions that underpin our analysis: whether
nitrogen deposition, and the nitrogen emissions behind it, can be classified
13
See Michael J. Bean, The Endangered Species Act and Private Land: Four Lessons
Learned from the Past Quarter Century, 28 Envtl. L. Rep. (Envtl. Law Inst.) 10,701, 10,705
(1998); Bean, supra note 5, at 41214; J. B. Ruhl, Climate Change and the Endangered Spe-
R
cies Act: Building Bridges to the No-Analog Future, 88 B.U. L. R
EV
. 1, 1416 (2008) [herein-
after Ruhl, Climate Change].
14
See Donald C. Baur, Comment on Climate Change and the Endangered Species Act:
Building Bridges to the No-Analog Future, 39 Envtl. L. Rep. (Envtl. Law Inst.) 10,746,
10,74748 (2009); J. B. Ruhl, Keeping the Endangered Species Act Relevant, 19 D
UKE
E
NVTL
.
L. & P
OL
Y
F. 275, 275, 27980 (2009) [hereinafter Ruhl, Endangered Species Act].
15
For discussion of GHG emissions and the ESA, see R
OBERT
M
ELTZ
, C
ONG
. R
ESEARCH
S
ERV
., RS22906, U
SE OF THE
P
OLAR
B
EAR
L
ISTING TO
F
ORCE
R
EDUCTION OF
G
REENHOUSE
G
AS
E
MISSIONS
: T
HE
L
EGAL
A
RGUMENTS
(2008), available at http://nepinstitute.org/get/CRS_
Reports/CRS_Climate_and_Environment/Other_Greenhouse_Gas_Emissions/Use_of_the_Po-
lar_Bear_listing_to_force_reduction_of_Greenhouse_Gas_Emissions.pdf; Baur, supra note
14; Matthew Gerhart, Climate Change and the Endangered Species Act: The Difficulty Of
R
Proving Causation, 36 E
COLOGY
L.Q. 167 (2009); Wm. Robert Irvin, Comment on Climate
Change and the Endangered Species Act: Building Bridges to the No-Analog Future, 39 Envtl.
L. Rep. (Envtl. Law Inst.) 10,750 (2009); Sarah Jane Morath, The Endangered Species Act: A
New Avenue for Climate Change Litigation, 29 P
UB
. L
AND
& R
ESOURCES
L. R
EV
. 24 (2008);
Ruhl, Climate Change, supra note 13; Ruhl, Endangered Species Act, supra note 14, at
R
27677; and Ari N. Sommer, Taking the Pit Bull Off the Leash: Siccing the Endangered Spe-
cies Act on Climate Change, 36 B.C. E
NVTL
. A
FF
. L. R
EV
. 273 (2009).
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438 Harvard Environmental Law Review [Vol. 35
and prosecuted as a violation of the take prohibition of the ESA. Put differ-
ently, do nitrogen emissions cause the type of habitat modification that can
qualify as harm under section 9 of the ESA? If so, how would a court or
regulator go about attributing the responsibility for such harm, given the
numerous stationary and mobile sources of such emissions? In addition to
building on relevant case law, we tackle these questions through a compari-
son between the ESA case against nitrogen deposition and the ESA case
against GHG emissions, specifically the possibility of restricting GHG emis-
sions as a prohibited take of polar bears and other climate-change-afflicted
threatened and endangered species. Part V addresses the second key ques-
tion in our analysis: whether and how the mandates and prohibitions of ESA
section 7 apply to federal actions that cause or permit nitrogen emissions.
The similarities and differences that emerge from juxtaposing the case
of nitrogen deposition with that of GHGs suggest there are more robust legal
and practical arguments for using the ESA to help control nitrogen emissions
than there are for leveraging the ESA in the policy and regulatory struggle
against GHG emissions and climate change.
In Part VI, the Article ultimately concludes that while it will be quite
challenging to show that nitrogen emissions, nitrogen deposition, and the
resulting modification of checkerspot habitat constitute harm and prohibited
take of checkerspots under section 9 of the Act, such a showing is not alto-
gether implausible. The Article also concludes that the use of section 9 as a
way to address nitrogen emission impacts on sensitive species and ecosys-
tems should be considerably facilitated by two key factors. First, the ulti-
mate responsibility for most offending emissions lies with a relatively small
number of federal and state air quality and pollution control agencies, rather
than with potentially countless individual and corporate actors (whose ability
to legally emit is effectively contingent on some form of license from these
agencies). Second, unlike GHGs, nitrogen emissions and ambient nitrogen
stay fairly regional in their movements and impact.
Finally, the Article notes that the greatest value of the ESA as a tool for
mitigating the impacts of nitrogen deposition may ultimately come from sec-
tion 7, and particularly from section 7’s potential to prod the U.S. Environ-
mental Protection Agency (“EPA”) into considering the species and habitat
implications of nitrogen emissions when it sets ambient air quality standards
under the Clean Air Act (“CAA”). Section 7 may also have a latent capac-
ity to motivate EPA to seek productive new ways of working with the states
in order to minimize the practical and administrative hurdles of improving
protections for nitrogen-sensitive habitats and species.
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2011] Tzankova et al., Nitrogen Deposition 439
II. N
ITROGEN
D
EPOSITION AND
I
TS
I
MPACTS ON
THE
T
HREATENED
C
HECKERSPOT
A. Ecological Impacts of Nitrogen Deposition
In the last century, human activity has introduced an unprecedented
amount of biologically available nitrogen into the environment. This trend is
expected to continue over the coming decades.
16
Introduction of biologically
available nitrogen results from several types of activities, most importantly
fossil fuel combustion, intensive animal agriculture, artificial production of
nitrogen fertilizer, and the cultivation of nitrogen-fixing legumes.
17
Only
recently have we started to understand the ecological impacts of such
human-caused nitrogen deposition, impacts that reach across a wide variety
of taxa and ecosystem types including lichens, mycorrhizae, forests, grass-
lands, arid and semi-arid deserts, and alpine ecosystems.
18
Across these sys-
tems, worldwide, the generation and redistribution of biologically available
nitrogen is altering ecosystem functions and the composition of natural plant
assemblages.
19
Increased atmospheric deposition of biologically available
nitrogen can increase the availability of nutrients, promoting increased car-
bon sequestration and plant growth.
20
At the same time, however, increased
nitrogen deposition often changes the competitive interactions among plants,
leading to a reduction in biodiversity and an increase in vulnerability to in-
vasion by non-native species. Nitrogen accumulation in excess of biological
demand can also disrupt ecosystem functioning by causing soil and water
acidification, increasing the loss of nutrients from the soil, and causing nutri-
ent imbalances in vegetation.
21
Such disruptions can clearly be seen in the
case of the checkerspot’s serpentine habitat.
16
James N. Galloway et al., Nitrogen Cycles: Past, Present, and Future, 70 B
IOGE-
OCHEMISTRY
153, 15355 (2004); James N. Galloway et al., Transformation of the Nitrogen
Cycle: Recent Trends, Questions, and Potential Solutions, 320 S
CI
. 889, 88990 (2008).
17
See Peter M. Vitousek et al., Human Alteration of the Global Nitrogen Cycle: Sources
and Consequences, 7 E
COLOGICAL
A
PPLICATIONS
737, 73839 (1997).
18
See Bobbink et al., Global Assessment, supra note 9, at 32.
R
19
These alterations are occurring through growth-stimulating as well as phytotoxic ef-
fects. Id. at 53; Roland Bobbink & Jan G. M. Roelofs, Nitrogen Critical Loads for Natural
and Semi-Natural Ecosystems: The Empirical Approach, 85 W
ATER
A
IR AND
S
OIL
P
OLLUTION
2413, 241516 (1995); Peter J. Lea, Oxides of Nitrogen and Ozone: Can Our Plants Survive?
139 N
EW
P
HYTOLOGIST
25 (1998); J. Pearson & A. Soares, A Hypothesis of Plant Susceptibil-
ity to Atmospheric Pollution Based on Intrinsic Nitrogen Metabolism: Why Acidity Really Is
the Problem, 85 W
ATER
A
IR AND
S
OIL
P
OLLUTION
1227, 123132 (1995); Vitousek et al.,
supra note 17, at 737; Alan R. Wellburn, Why Are Atmospheric Oxides of Nitrogen Usually
R
Phytotoxic and Not Alternative Fertilizers? 115 N
EW
P
HYTOLOGIST
395, 395 (1990).
20
Nitrogen-based fertilizers are used in agriculture for this very reason. For the plant
growth impacts of nitrogen deposition in natural ecosystems, see, for example, Peter A. Beed-
low et al., Rising Atmospheric CO
2
and Carbon Sequestration in Forests, 2 F
RONTIERS IN
E
COLOGY
&
THE
E
NV
T
315 (2004).
21
Gregory P. Asner et al., The Decoupling of Terrestrial Carbon and Nitrogen Cycles, 47
B
IO
S
CIENCE
226 (1997); Bobbink et al., Air-Borne Nitrogen Pollutants, supra note 8; Frank S.
R
Gilliam, Response of the Herbaceous Layer of Forest Ecosystems to Excess Nitrogen Deposi-
tion, 94 J. E
COLOGY
1176 (2006); Phoenix et al., supra note 7; Vitousek et al., supra note 17;
R
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440 Harvard Environmental Law Review [Vol. 35
B. The Impacts of Nitrogen Deposition on Bay Area Serpentine
Grasslands and Their Threatened Checkerspot Inhabitants
The checkerspots’ historical range spanned the entire San Francisco Bay
Area, stretching from San Bruno Mountain to Mount Diablo to Coyote Res-
ervoir, across seven Bay Area counties.
22
However, following local extinc-
tions of checkerspot populations driven by habitat degradation and loss from
grazing and development, the checkerspot range is currently much smaller; it
is, in fact, restricted to one Bay Area county: Santa Clara County.
23
Ex-
tremely habitat-limited, the checkerspot is found solely in Bay Area serpen-
tine grasslands; the checkerspot’s habitat, then, is precisely the type of
ecosystem most vulnerable to increases in nitrogen deposition.
24
Such in-
creases are currently being produced by fossil fuel emissions in the growing
San Francisco Bay Area.
25
The sensitivity of serpentine grasslands to nitrogen deposition is due to
the fact that serpentine-derived soils are characterized by relatively low ra-
tios of calcium to magnesium and low nutrient availability.
26
As such, these
soils support edaphically isolated communities of unique plant and animal
species, and are generally able to resist invasion by the non-native and inva-
sive plant species that are prevalent throughout other California grasslands.
27
The addition of soil nitrogen in serpentine ecosystems, however, has been
found to facilitate the invasion and dominance of non-native annual grasses
in patches of serpentine habitat originally dominated by native annual
forbs.
28
In other words, excess nitrogen deposition can alter plant communi-
ties and habitats by facilitating the encroachment of fast growing non-native
species that can then overwhelm or exclude the slower growing native
plants.
Decline in native species diversity, in turn, can have cascading effects
on herbivore populations, such as the remaining checkerspot populations,
Charles T. Driscoll et al., Nitrogen Pollution in the Northeastern United States: Sources, Ef-
fects, and Management Options, 53 B
IO
S
CIENCE
357 (2003).
22
U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 2; see also Dennis D. Murphy & Paul R.
R
Ehrlich, Two California Checkerspot Butterfly Subspecies: One New, One on the Verge of
Extinction, 34 J
OURNAL OF THE
L
EPIDOPTERISTS
’ S
OCIETY
316, 31618 (1980).
23
U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 2.
24
See Weiss, Cars, Cows, and Checkerspot Butterflies, supra note 5, at 148385; U.S.
R
F
ISH
& W
ILDLIFE
S
ERV
., supra note 3, at 17582, 19395; U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra
R
note 1, at 1011, 13.
R
25
Mark E. Fenn et al., Nitrogen Emissions, Deposition, and Monitoring in the Western
United States, 53 B
IOSCIENCE
391, 39596 (2003); P
UBLIC
D
RAFT
, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
P
LAN
, App. E at E-1E-3 (December 17, 2010) , available at http://www.scv-habitat
plan.org/www/site/alias__default/341/public_draft_habitat_plan.aspx.
26
Kathleen M. Kay et al., Plant Speciation, in S
ERPENTINE
: T
HE
E
VOLUTION AND
E
COL-
OGY OF A
M
ODEL
S
YSTEM
71, 7375 (Susan Harrison & Nishanta Rajakaruna eds., 2011).
27
U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 1011; Huenneke et al., supra note 6, at
R
479.
28
Huenneke et al., supra note 6, at 478.
R
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 9 19-JUL-11 14:54
2011] Tzankova et al., Nitrogen Deposition 441
which depend on native plants.
29
The primary larval host plant for the
checkerspot is a small annual forb a native dwarf plantain (Plantago er-
ecta) but checkerspot larvae can also take some advantage of two secon-
dary host plants, denseflower Indian paintbrush (Castilleja densiflora) and
exserted Indian paintbrush (Castilleja exserta), since these remain edible
longer than the plantain.
30
Key for the subsequent discussion, the checkerspot has a complex,
multi-stage life cycle whose successful completion depends on the availabil-
ity of habitat and resources most importantly, the availability of the host
plants that serve for oviposition and larval food during the early stages of
larval development. Once checkerspot larvae, which are oviposited on the
native plantain, reach the fourth stage of larval development, they enter a
dormancy stage and stay dormant for the summer season.
31
Successfully
reaching the dormancy stage significantly depends on the availability of suf-
ficient food resources from the native host plants.
32
The checkerspot larvae
are further reliant on host plants for food as they break out of the dormancy
stage and continue to feed until they pupate and eventually become adult
butterflies.
33
This makes any nitrogen-driven displacement of native host
plants (most importantly, the dwarf plantain) a potential threat to the suc-
cessful completion of the checkerspot’s reproductive cycle, and therefore, to
the continued existence of this already threatened species.
At the same time, a growing body of ecological evidence suggests that
nitrogen deposition, much of it from regional fossil fuel emissions,
34
is a key
factor behind the rapid recent invasion of the highly diverse Bay Area
serpentine ecosystems by exotic annual grasses.
35
This nitrogen-aided inva-
sion of exotic annual grasses is progressively eliminating rare and endemic
serpentine species, including several federally listed plant species as well as
the dwarf plantain (the primary food source for checkerspot larvae).
36
C. Sources of Nitrogen Deposition on Bay Area Serpentine Grasslands
The nitrogen emissions responsible for nitrogen deposition of the nutri-
ent-poor serpentine grasslands come from a range of sources, including
power plants, boilers, stationary turbines and engines, motor vehicles, and
29
W
EISS
, I
MPACTS OF
N
ITROGEN
D
EPOSITION
, supra note 5, at 51; Bobbink et al., Global
R
Assessment, supra note 9, at 38.
R
30
Michael C. Singer, Complex Components of Habitat Suitability within a Butterfly Col-
ony, 176 S
CIENCE
75 (1972); Murphy & Ehrlich, supra note 22 at 31617; Weiss, Cars, Cows,
R
and Checkerspot Butterflies, supra note 5, at 1478; U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1,
R
at 2.
31
U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 2, 79.
R
32
See, e.g., Murphy & Weiss, supra note 3, at 189; U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra
R
note 1, at 69.
R
33
Id.
34
See Weiss, Cars, Cows, and Checkerspot Butterflies, supra note 5, at 1476.
R
35
Id. at 1483.
36
Id.
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 10 19-JUL-11 14:54
442 Harvard Environmental Law Review [Vol. 35
agricultural activities.
37
These emissions primarily include the ongoing rise
in atmospheric nitrogen oxides (“NO
x
”) from fossil fuel combustion, and
especially nitrogen dioxide (“NO
2
”) a criteria pollutant regulated under
the CAA and ammonia gases (“NH
x
”) from agricultural emissions and
animal husbandry.
38
In the airshed relevant to serpentine grasslands and
their checkerspot inhabitants, however, ammonia (“NH
3
”) is emitted in sig-
nificant amounts from motor vehicles: ammonia is currently an unregulated
byproduct of three-way catalytic converters, which were introduced to abate
combustion-source emissions of pollutants like carbon monoxide, hydrocar-
bons, and nitric oxide.
39
Together, these emissions have significantly in-
creased the input of both wet and dry nitrogen deposition (in the form of
precipitation and gaseous deposition, respectively) to typically nitrogen-lim-
ited serpentine grassland ecosystems.
40
In areas in the vicinity of checkerspot habitat, an estimated 42% of
nitrogen deposition comes from gaseous dry deposition of NO
x
, 48%
originates from by-products of atmospheric NO
x
transformations (particulate
nitrate and nitric acid vapor), while the remaining 10% comes from NH
x
.
41
Some of the emissions responsible for nitrogen deposition on checkerspot
habitat come from outside Santa Clara county (where the remaining checker-
spot populations are exclusively found). Modeled estimates suggest that the
remainder of Bay Area counties contribute 11% of such nitrogen deposition,
while nitrogen-emitting activities in the rest of California and portions of
Nevada are considered responsible for 26% of current atmospheric
deposition.
42
Importantly, the observed nitrogen-driven changes to the checkerspot
serpentine habitat have largely occurred in a context of long-term compli-
ance with federal and state air quality standards for NO
x
. That is, the ob-
served negative impacts on the checkerspot and its serpentine habitat are
occurring in a context where regulated nitrogen emissions have been within
the parameters of what EPA has determined as acceptable under the CAA
37
P
UBLIC
D
RAFT
, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
P
LAN
, supra note 25, at App. E, E-
R
79E-81.
38
EPA, I
NTEGRATED
S
CIENCE
A
SSESSMENT
F
OR
O
XIDES
O
F
N
ITROGEN
A
ND
S
ULFUR
- E
CO-
LOGICAL
C
RITERIA
, F
INAL
R
EPORT
,
AT
2-22-7 (2008).
39
See, e.g., Gary A. Bishop et al., On-Road Emission Measurements of Reactive Nitrogen
Compounds from Three California Cities, 44 E
NVTL
. S
CI
. T
ECH
. 3616, 3616 (2010); A.J. Kean
et al., Trends in On-Road Vehicle Emissions of Ammonia, 43 A
TMOSPHERIC
E
NV
T
1565, 1565
(2009).
40
See Fenn et al., Ecological Effects, supra note 7, at 416. Both NO
x
and NH
x
pollutants
R
have relatively short atmospheric lifetimes (hours to days) and are typically deposited locally
near point sources of pollution, but both are also capable of being converted to longer-lived
forms and transported across regional scales. See Fenn et al., supra note 25, at 39899.
R
41
Current emissions estimates do not yet take into account several contributing point and
non-point sources, such as off-road vehicles, small area sources, and agricultural and animal
husbandry emissions. Fenn et al., supra note 25, at 401; EPA, supra note 38, at 2-22-7.
R
42
P
UBLIC
D
RAFT
, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
P
LAN
, supra note 25, Appendix E at E-
R
2.
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2011] Tzankova et al., Nitrogen Deposition 443
and also within the parameters of the somewhat stricter ambient standards
set by the California Air Resources Board (“CARB”).
43
III. T
HE
E
NDANGERED
S
PECIES
A
CT
: A B
RIEF
O
VERVIEW
The opening sections of the ESA offer an unambiguous statement of the
congressional purpose behind the statute. The Act is intended to “provide a
means whereby the ecosystems upon which endangered species and
threatened species depend may be conserved” and “to provide a program for
the conservation of such endangered species and threatened species.”
44
Although many historical analyses suggest that at the time of the ESA’s
passage Congress was not fully aware of the statute’s actual scope and impli-
cations, or the numerous regulatory and legal controversies that its imple-
mentation would set into motion, the ESA has become a key pillar of United
States conservation policy. In addition to its direct species protection value,
the ESA has been used as a tool to combat suburban and exurban sprawl into
wildlands and open space and as a tool to nudge conservation-beneficial land
use planning.
45
It also holds some important (if arguably insufficient) poten-
tial to help protect biodiversity on working landscapes,
46
and it has aided in
the protection of working seascapes.
47
Indeed, hardly a discussion of the
ESA goes by without mention of its status as “the pit bull of environmental
43
See Primary National Ambient Air Quality Standards for Nitrogen Dioxide, 75 Fed.
Reg. 6474, 6476 (Feb. 9, 2010) (to be codified at 40 C.F.R. pts. 50, 58) (“Currently there are
no areas in the United States that are designated as nonattainment of the NO
2
NAAQS.”);
C
ALIF
. A
IR
R
ES
. B
D
., C
HRONOLOGY OF
S
TATE
N
ITROGEN
D
IOXIDE
D
ESIGNATIONS
(2010),
available at http://www.arb.ca.gov/desig/changes/no2.pdf; C
ALIF
. A
IR
R
ES
. B
D
., 2010 A
REA
D
ESIGNATIONS FOR
S
TATE
A
MBIENT
A
IR
Q
UALITY
S
TANDARDS
N
ITROGEN
D
IOXIDE
(2010),
available at http://www.arb.ca.gov/desig/adm/adm.htm; Air Quality Standards and Attainment
Status, B
AY
A
REA
A
IR
Q
UALITY
M
GMT
. D
IST
., http://www.arb.ca.gov/desig/adm/2010/state_
no2.pdf (last visited Feb. 28, 2011) (on file with the Harvard Law School Library). There is
currently no data, however, on the extent of compliance with EPA’s newly introduced short-
term, one-hour NO
2
standard, in force since January 22, 2010. See Primary National Ambient
Air Quality Standards for Nitrogen Dioxide, 75 Fed. Reg. 6474 (Feb. 9 2010). It is entirely
possible that areas which have been in compliance with the long-standing (and essentially less
strict) annual NO
2
standard of 53 parts per billion will need to make further adjustments in
their current emission controls in order to comply with the stricter new NO
2
standard.
44
16 U.S.C. § 1531(b) (2006).
45
See Thomas A. Scott et al., Land Use Planning, in 2 T
HE
E
NDANGERED
S
PECIES
A
CT AT
T
HIRTY
206, 21617 (J. Michael Scott et al. eds., 2006); Karen Donovan, HCPs Important
Tools for Conserving Habitat and Species, in E
NDANGERED
S
PECIES
A
CT
: L
AW
, P
OLICY
,
AND
P
ERSPECTIVES
319 (Donald C. Baur & Wm. Robert Irvin eds., 2002); see also Stephanie
Pincetl, Conservation Planning in the West, Problems, New Strategies and Entrenched Obsta-
cles, 37 G
EOFORUM
246, 25051 (2006).
46
Burton H. Thompson Jr., Managing the Working Landscape, in 1 T
HE
E
NDANGERED
S
PECIES
A
CT AT
T
HIRTY
101, 12425 (J. Michael Scott et al. eds., 2006).
47
See Paul R. Armsworth et al., Working Seascapes, in 2 T
HE
E
NDANGERED
S
PECIES
A
CT
AT
T
HIRTY
, supra note 45, at 244, 25155.
R
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 12 19-JUL-11 14:54
444 Harvard Environmental Law Review [Vol. 35
laws,”
48
even if normative judgments as to whether this pit-bullishness is a
good thing or a bad thing tend to vary.
At its core, the ESA provides several key mechanisms for the protec-
tion of imperiled species and the ecosystems on which they depend. First, in
order to benefit from the ESA’s protection, a species has to be listed by one
of the implementing agencies the FWS or NOAA’s National Marine Fish-
eries Service (“NMFS”)
49
as threatened or endangered.
50
Once a species
has been listed as threatened or endangered, it gets specific protections under
sections 7 and 9 of the ESA. Section 7 of the ESA requires each federal
agency to ensure that its actions do not jeopardize the continued existence of
threatened or endangered species or adversely modify the designated critical
habitat of such species.
51
Agencies are to do so in consultation with the
FWS or NMFS.
52
Section 7 also establishes affirmative duties for species
protection, asking federal agencies to “utilize their authorities in furtherance
of the purposes of [the ESA] by carrying out programs for the conservation
of endangered species and threatened species.”
53
Section 9, meanwhile, prohibits the take of listed wildlife
54
by private
actors and government agencies alike, which has potentially far-reaching
practical consequences given the broad definition of “take”
55
and the numer-
48
The metaphor was originally coined by Don Barry, an Assistant Secretary for Fish,
Wildlife, and Parks in the Department of the Interior. Bean, supra note 13, at 10701.
R
49
The FWS and NMFS share responsibility for administering the ESA. 50 C.F.R.
§ 402.01(b) (2010).
50
An endangered species is defined in the ESA as “any species which is in danger of
extinction throughout all or a significant portion of its range other than a species of the Class
Insecta determined by the Secretary to constitute a pest whose protection under the provisions
of this chapter would present an overwhelming and overriding risk to man.” 16 U.S.C.
§ 1532(6) (2006). A threatened species is defined as “any species which is likely to become
an endangered species within the foreseeable future throughout all or a significant portion of
its range.” 16 U.S.C. § 1532(20) (2006). The criteria for listing species as threatened or
endangered, as well as mandates for recovery planning and the designation of critical habitat
for listed species are provided in section 4 of the ESA. 16 U.S.C. § 1533 (2006). Section 4
also enables citizens to petition the agency for the listing or delisting of species. 16 U.S.C.
§ 1533(b)(3)(A) (2006).
51
16 U.S.C. § 1536(a)(2) (2006).
52
Id.
53
16 U.S.C. § 1536(a)(1) (2006). For further discussion of the importance and conserva-
tion potential of these frequently overlooked section 7(a)(1) provisions, see J.B. Ruhl, Section
7(a)(1) of the “New” Endangered Species Act: Rediscovering and Redefining the Untapped
Power of Federal Agencies’ Duty to Conserve Species, 25 E
NVTL
. L. 1107 (1995).
54
16 U.S.C. § 1538(a)(1) (2006). Plants get much weaker protections under section 9. 16
U.S.C. § 1538(a)(2) (2006). For more detail, see infra notes 6872 and accompanying text.
R
55
The statute defines a “take” of listed wildlife to mean harassing, harming, pursuing,
hunting, shooting, wounding, killing, trapping, capturing, or collecting such wildlife and/or
attempting to engage in any such conduct. 16 U.S.C. § 1532(19) (2006). The FWS regula-
tions interpret the term broadly, noting that “harm in the definition of ‘take’ in the [Endan-
gered Species] Act means an act which actually kills or injures wildlife. Such acts may
include significant habitat modification or degradation where it actually kills or injures wildlife
by significantly impairing essential behavioral patterns, including breeding, feeding or shelter-
ing.” 50 C.F.R. § 17.3 (2010).
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 13 19-JUL-11 14:54
2011] Tzankova et al., Nitrogen Deposition 445
ous actions including many otherwise ordinary land uses that could
lead to a prohibited take.
Some exemptions from the categorical prohibitions set forth in sections
7 and 9 are laid out in section 10 of the Act.
56
Most important among these
is the take exemption in section 10(a),
57
introduced as part of the 1982 ESA
amendments. Created at the request of a “coalition of developers, municipal
governments, and a local environmental organization,”
58
section 10 has in-
troduced opportunities for reconciling the needs of species and habitat pro-
tections with the needs of economic use and development.
59
Specifically,
section 10(a) establishes conditions for permitting some incidental take of
listed wildlife.
60
A take of listed wildlife can be permitted only if it is inci-
dental to, and not the purpose of, an otherwise lawful activity and would
“not appreciably reduce the likelihood of the survival and recovery of the
species” in the wild.
61
Section 10(a) also sets up a process for the permitting
of such incidental take a process which requires the preparation of a
conservation plan by the private and government actors whose activities are
expected to produce such a take.
62
The plan has to be approved by the FWS
or NMFS, who each have a fair amount of discretion to impose additional
terms and conditions.
63
IV. N
ITROGEN
D
EPOSITION AS A
P
ROHIBITED
T
AKE OF
C
HECKERSPOTS
?
Does the long-standing if relatively unnoticed phenomenon of nitrogen
deposition on Bay Area serpentine grasslands represent a violation of key
56
16 U.S.C. § 1539 (2006).
57
16 U.S.C. § 1539(a) (2006).
58
Robert L. Fischman & Jaelith Hall-Rivera, A Lesson for Conservation from Pollution
Control Law: Cooperative Federalism for Recovery Under the Endangered Species Act, 27
C
OLUM
. J. E
NVTL
. L. 45, 69 (2002).
59
Donovan, supra note 45 at 32021; Fischman & Hall-Rivera, supra note 58, at 7576;
R
see also Blaine I. Green, The Endangered Species Act and Fifth Amendment Takings: Constitu-
tional Limits of Species Protection, 15 Y
ALE
J.
ON
R
EG
. 329, 33233, 36775 (1998).
60
16 U.S.C. 1539(a) (2006).
61
16 U.S.C. § 1539(a)(2)(B) (2006)
62
See 16 U.S.C. § 1539(a)(1) (2006). Also, take is only permitted after the FWS ap-
proves the conservation plan prepared by the permit applicant. Incidental take permits are
essentially issued in exchange for preparing and funding the implementation of a conservation
plan for the species affected by the proposed activity. Conservation plans must specify the
likely species impact of the proposed incidental taking, the alternatives to the proposed take
and reasons why the alternatives are not feasible, the steps that the applicant will take to
minimize and mitigate the impacts resulting from his/her taking of listed wildlife, the funding
that will be made available to take such mitigation steps, and any other measures that the FWS
considers necessary. 16 U.S.C. § 1539(a)(2) (2006).
63
For details on the implementation and implications of section 10(a) incidental take and
habitat conservation planning provisions, see Karin P. Sheldon, Habitat Conservation Plan-
ning: Addressing the Achilles Heel of the Endangered Species Act, 6 N.Y.U. E
NVTL
. L.J. 279
(1998), John F. Turner & Jason C. Rylander, Conserving Endangered Species on Private
Lands, 32 L
AND
& W
ATER
L. R
EV
. 571, 57784 (1997), and C
RAIG
W. T
HOMAS
, Bureaucratic
Landscapes: Interagency Cooperation and the Preservation of Biodiversity 193226 (2003).
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446 Harvard Environmental Law Review [Vol. 35
provisions of the ESA? This section examines the impacts of nitrogen depo-
sition against the ESA prohibition on taking of listed species. Specifically,
this section aims to situate the impacts of nitrogen deposition within the
highly contested legal territory of take via habitat modification. First, it
highlights key points of contention regarding the practical application of the
“take” prohibition established in section 9 of the ESA. It then considers the
implications of such ongoing legal controversies for the question of whether
nitrogen deposition is a form of prohibited harm of checkerspots. Finally, it
evaluates the legal and practical plausibility of treating nitrogen deposition
as a prohibited take of checkerspots, in part by comparing the case of the
checkerspot to another recently developed ESA case that considers GHG
emissions as a possible take of threatened polar bears and other listed spe-
cies whose habitats are degraded by GHG-driven climate change.
64
Current government efforts have considered protecting the checkerspot
from the effects of nitrogen deposition. However, these efforts have retained
focus on the traditional regulation of direct harm to habitats. The plausibil-
ity of considering nitrogen deposition as harm, and thus a prohibited take, of
checkerspots is implicit in the content of the regional Santa Clara Valley
Habitat Plan (“SCV HP”), developed over the past several years by a coali-
tion of government agencies in the Santa Clara Valley.
65
The SCV HP con-
siders nitrogen deposition and its checkerspot consequences in quite some
detail.
66
However, the primary focus of the SCV HP is on anticipating, mini-
mizing, and mitigating harm to listed species as a result of added future
development, rather than addressing nitrogen emissions associated with cur-
rent development and related activities.
67
This focus limits the reach and
significance of any precedent that might be set by the SCV HP. Further, the
SCV HP cannot reach nitrogen emissions that occur outside the planning
area but still deposit on serpentine grasslands within the area. The analysis
in this Article, focusing on the threat to the checkerspot from nitrogen depo-
64
The subject of some lively and thoughtful legal discussion since the polar bear’s listing
in 2008, the ESA case against GHG emissions has been thoughtfully and thoroughly consid-
ered by several legal scholars and practitioners. See sources cited supra note 15.
R
65
Partners include Santa Clara County, the Santa Clara Valley Transportation Authority,
the Santa Clara Valley Water District, and the cities of Gilroy, San Jose, and Morgan Hill. See
Project Partners, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
P
LAN
, http://www.scv-habitatplan.org/
www/site/alias__default/297/project_partners.aspx (last visited Feb. 7, 2011).
66
P
UBLIC
D
RAFT
, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
P
LAN
, supra note 25, at 4-744-76.
R
67
The SCV HP recognizes that increases in vehicle trips associated with projected future
development will increase nitrogen deposition, which negatively impacts covered species. The
chain of connection between development, vehicle trips, nitrogen emissions, nitrogen deposi-
tion, and modification of covered species’ habitats is part though certainly not all of the
justification for imposing the development fees that are both a major component of the SCV
HP and a major source of its funding. None of the discussions in the SCV HP explicitly
classify the indirect effects of nitrogen deposition as a prohibited take, but the plan does seem
to have been written with an awareness that nitrogen deposition associated with covered activi-
ties might prevent the success of the plan’s conservation goals. P
UBLIC
D
RAFT
, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
P
LAN
, supra note 25, Chapt. 4 at 4-3, 4-32, 4-63, 4-664-68, 4-734-75, 4-
R
110 & app. E, E-1E-3.
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2011] Tzankova et al., Nitrogen Deposition 447
sition and how the ESA applies to this danger, is important and timely be-
cause it fills this gap in the existing analysis.
A. “Harm” and “Take” Under the Current ESA Regime
Section 9 of the ESA prohibits the taking of any endangered species of
fish and wildlife.
68
This prohibition applies to the actions of private individ-
uals and businesses as well as those of government agencies and employ-
ees.
69
It protects endangered species of fish and wildlife regardless of
whether they are found on public or private lands. The FWS has passed
regulations that further extend these section 9 protections to threatened spe-
cies.
70
The statute defines a “take” to include harassing, harming, pursuing,
hunting, shooting, wounding, killing, trapping, capturing, or collecting such
wildlife or attempting to engage in any such conduct.
71
Most aspects of the statutory definition of take are fairly uncontrover-
sial. Little disagreement has, for example, occurred when it comes to gaug-
ing whether or not a particular act qualifies as an instance of hunting,
shooting, or trapping. The question of what it means to harm a listed species
in ways prohibited by the statute, on the other hand, has produced the deep-
est, longest standing, and still incompletely resolved disagreements. The
meaning of “harm” has thus become the crux of disputes about the reach
and practical application of section 9 protections. At the heart of the
controversy is the issue of harm via habitat modification. This is the precise
issue at stake in the checkerspot case. The FWS regulations specify that
harm in the definition of ‘take’ in the [Endangered Species] Act means an
act which actually kills or injures wildlife. Such act may include significant
habitat modification or degradation where it actually kills or injures wildlife
by significantly impairing essential behavioral patterns, including breeding,
feeding or sheltering.”
72
What does this spell for the checkerspot? As discussed in Part II above,
current ecological knowledge strongly supports the significance of nitrogen
deposition for the profound alteration of nutrient poor serpentine grasslands
the only remaining checkerspot habitat by invading non-native
68
16 U.S.C. § 1538(a) (2006).
69
16 U.S.C. §§ 1532(B), 1538(A) (2006).
70
50 C.F.R. § 17.31(a) (2010). NMFS, on the other hand, stipulates protections for the
threatened species under its jurisdiction on a case-by-case basis. See 50 C.F.R. § 223.20111
(2010). Both agencies’ authority to extend further protections to threatened species stems from
section 4(d) of the ESA. 16 U.S.C. § 1533(d) (2006). It is important to note that the “take”
prohibition does not generally apply to listed plants. The ESA makes the taking of listed
plants unlawful on federal lands; taking of listed plants on private land is unlawful only if it is
already prohibited under state species protection laws or regulations. 16 U.S.C.
§ 1538(a)(2)(B) (2006). That is, section 9 of the ESA is intended to help enforce state plant
protection laws, but does not itself provide equivalent protection for plants. Plants are, on the
other hand, treated the same as fish and wildlife under section 7 of the ESA. See 16 U.S.C.
§ 1536 (2006).
71
16 U.S.C. § 1532(19) (2006).
72
50 C.F.R. § 17.3 (2010) (emphasis added).
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448 Harvard Environmental Law Review [Vol. 35
grasses. The nitrogen-aided non-native grasses have been observed to dis-
place the dwarf plantain on which the checkerspot depends for oviposition
and on which checkerspot larvae largely depend for food.
73
Such nitrogen-
aided invasive grass displacement of larval host plants has, in turn, been
observed to produce increased larval mortality and dramatic declines in
checkerspot populations.
74
Another potential result of nitrogen deposition on checkerspot habitat
may be increased competition among checkerspot individuals for the re-
maining suitable habitat including competition for food and plants on
which to lay their eggs. Related, although as yet undocumented due to the
ethical and logistical challenges of using listed species for research, there is
the possibility that host plant displacement and habitat loss may also lead to
foregone or thwarted oviposition by checkerspot adults: since checkerspots
need to lay their eggs on plantain, not finding enough individual plantains
means that checkerspots may not lay their eggs at all, or that they lay them
on the wrong species, where the larvae will die from starvation.
In other words, nitrogen deposition is detrimental to the checkerspot’s
serpentine habitat, and is ultimately bad for the checkerspot itself. Indeed,
the impact of nitrogen-driven habitat change has been, in the FWS’s own
assessment, an important factor in the continued decline of remaining check-
erspot populations.
75
Can current patterns of nitrogen emissions and deposition be considered
a prohibited take of protected checkerspots? Based on the series of nitrogen
impacts on checkerspot habitat and checkerspot behavior, the answer may
seem quite simple: yes. However, determining whether the effects of nitro-
gen emissions on checkerspot habitat can be considered a “harm” involves
the question of whether a particular habitat modification constitutes the type
of injury to listed wildlife that is proscribed under section 9. Always con-
tested, the questions of what constitutes proscribed injury and what consti-
tutes prohibited harm have prompted pitched legal battles even when the
habitat modification in question has been fairly direct.
76
The existence of
harm through habitat modification becomes proportionately more difficult to
establish, and so potentially more controversial, when the habitat-related
harm occurs through a complex and indirect chain of causation, such as the
loss of Arctic sea ice driven by climate change or the change in high altitude
73
See Huenneke et al., supra note 6, at 48889; Weiss, Cars, Cows, and Checkerspot
R
Butterflies, supra note 5, at 147985; U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 2, 1011,
R
1315.
74
See Weiss, Cars, Cows, and Checkerspot Butterflies, supra note 5, at 147980; U.S.
R
F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 79; P
UBLIC
D
RAFT
, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
R
P
LAN
, supra note 25, app. D, at 3.
R
75
See U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 1415.
R
76
See, e.g., Bean, supra note 13, at 10,703 (discussing United States v. West Coast Forest
R
Res. Ltd. P’ship, No. 96-1575-HO, 1997 WL 33100698 (D. Or. Jul. 28, 1997) and Defenders of
Wildlife v. Bernal, 204 F.3d 920 (9th Cir. 2000)).
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2011] Tzankova et al., Nitrogen Deposition 449
montane habitats
77
or the complex chain of causation detailed above in
the checkerspot case.
The legal task of showing harm through habitat modification becomes
even more difficult when it comes to tracing the precise causal links between
the macro-scale phenomena known to be responsible for habitat modifica-
tion for example, climate change and nitrogen deposition and the
micro-scale acts of individual emitters, which are ultimately behind such
macro-scale phenomena.
78
Determining whether nitrogen emissions and ni-
trogen deposition can be reasonably treated as a prohibited take of checker-
spots ultimately requires us to gauge whether the habitat impacts of nitrogen
deposition meet the legal standard for harm through habitat modification
a standard that is potentially stricter and therefore more difficult to satisfy
than a biological standard for harm.
79
B. Habitat Modification as a Source of Harm to Protected Wildlife
Interpretations of harm under the ESA have varied over time and across
various courts and agencies. The FWS regulations that define harm to in-
clude some forms of habitat modification have been on the books since
1975, and the variation in judicial interpretations of these provisions is al-
most as old. At the opposite ends of such interpretations stand cases like
Sierra Club v. Froehlke
80
and Palila v. Hawaii Department of Land & Natu-
ral Resources (“Palila I”).
81
It was the Ninth Circuit’s broad interpretation
of harm via habitat modification in Palila I
82
that prompted the FWS to
77
See, e.g., M
ELTZ
, supra note 15, at 3; Ruhl, Climate Change, supra note 13, at 36;
R
Ruhl, Endangered Species Act, supra note 14, at 275; Gerhart, supra note 15, at 169.
R
78
See infra notes 122124 and accompanying text. For further discussion of the chal-
R
lenges attending attempts at linking macro-scale phenomena causing habitat change to the
micro-scale individual acts cumulatively triggering such macro-scale phenomena, see gener-
ally Gerhart, supra note 15, and Ruhl, Climate Change, supra note 13.
R
79
See Alan M. Glen & Craig M. Douglas, Taking Species: Difficult Questions of Proxim-
ity and Degree, 16 N
AT
. R
ESOURCES
& E
NV
T
65, 6566 (2001); see also Robert L. Fischman,
The Divides of Environmental Law and the Problem of Harm in the Endangered Species Act,
83 I
ND
. L.J. 661, 68490 (2008).
80
Sierra Club v. Froehlke, 392 F. Supp. 130 (E.D. Mo. 1975), aff’d, 534 F.2d 1289 (8th
Cir. 1976). In Sierra Club v. Froehlke, one of the earliest cases involving the question of harm
via habitat modification, the Eighth Circuit found that the construction of a dam and reservoir,
which would flood subterranean caverns inhabited by the endangered Indiana bat, was not a
violation of section 9 since the dam was clearly not intended to harass or harm the bats. Id. at
1304. In that court’s view, no intentionality meant no harm occurred regardless of the fact that
endangered bats would die. See also Kenneth J. Plante & Andrew J. Baumann, Babbit v.
Sweet Home Chapter of Communities for a Great Oregon: Preserving the “Critical Link”
Between Habitat Modification and the “Taking” of an Endangered Species, 20 N
OVA
L. R
EV
.
748, 75356 (1996).
81
Palila v. Hawaii Dep’t of Land & Natural Res. (Palila I), 471 F. Supp. 985 (D. Haw.
1979), aff’d, 639 F.2d 495 (9th Cir. 1981). In Palila I, the courts found that the destruction of
mamane-naio forests, as caused by the grazing of feral sheep and goats, was a prohibited take
of the endangered palila bird, since the alreadydeclining palila populations relied on the
mamane-naio forests for food and nesting. Palila I, 471 F.Supp. at 995.
82
Id. Commonly referred to as Palila I in the ESA literature, since an almost identical
issue was re-litigated in Palila v. Hawaii Dep’t of Land & Natural Res. (Palila II) after the
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450 Harvard Environmental Law Review [Vol. 35
revise its regulatory definition of harm. This 1981 revision (which produced
the current definition of harm)
83
was born out of the FWS’s concern that the
Palila I decision could be read to imply that habitat modification alone
without associated injury to the species can be considered harm and thus
a prohibited take.
84
Intended to eliminate the possibility for any such inter-
pretation, the new FWS definition reads, “harm in the definition of ‘take’ in
the [Endangered Species] Act means an act which actually kills or injures
wildlife. Such act[s] may include significant habitat modification or degra-
dation where it actually kills or injures wildlife by significantly impairing
essential behavioral patterns, including breeding, feeding or sheltering.”
85
In the now-famous case of Babbitt v. Sweet Home Chapter of Commu-
nities for a Great Oregon, the Supreme Court upheld the 1981 regulatory
clarification.
86
While the plaintiffs in the Sweet Home case challenged the
very notion that habitat modification can constitute a prohibited take of
listed wildlife, and thus challenged the validity of the FWS 1981 harm regu-
lation,
87
the Supreme Court’s 6-3 decision to uphold the regulation was built
on an analysis of the proper scope and interpretation of the challenged
regulation.
88
FWS promulgated a new definition of harm in 1981. 649 F. Supp. 1070 (D. Haw. 1986), aff’d,
852 F.2d 1106 (9th Cir. 1988).
83
50 C.F.R. § 17.3 (2010).
84
See Plante & Baumann, supra note 80, at 76465.
R
85
50 C.F.R. § 17.3 (2010) (emphasis added). Interestingly, the Palila I case was shortly
re-tried under this new definition and under almost identical circumstances, except this time, it
was introduced mouflon sheep (rather than the feral sheep and goats removed after Palila I)
that were grazing the palila habitat into destruction and helping nudge the palila closer to
extinction. The second time around, the case generated the same ruling, since the district court
hearing the case saw in the new definition nothing more than a clarification/reinforcement of a
proposition it considered already well-established under the old definition namely, that
habitat modification has to result in injury to protected wildlife before it becomes prohibited
take. Palila II, 649 F. Supp. at 1075, 1082. Notably, the Palila II court ruled that habitat
modification which could result in extinction does constitute harm and so a prohibited
“take,” regardless of whether such habitat modification has caused the death of individual
members from the protected species and it found that mouflon grazing was producing
precisely this type of habitat modification. Id. at 1075, 1078. The Ninth Circuit affirmed this
District Court ruling, thereby putting Palila II on the list of most discussed and most contro-
versial ESA cases. 852 F.2d 1106.
86
Babbitt v. Sweet Home Chapter of Cmtys. for a Great Or., 515 U.S. 687 (1995).
87
The Sweet Home plaintiffs claimed that, in including habitat modification as part of the
regulatory definition of “harm,” the FWS had exceeded its ESA authority. Id. at 693.
88
A detailed discussion of the Sweet Home opinion is outside the scope of the current
paper, especially since a number of thoughtful and thorough analysts have long since beaten us
to the task. See, e.g., Kevin D. Batt, Above All, Do No Harm: Sweet Home and Section Nine
of the Endangered Species Act, 75 B.U. L. R
EV
. 1177 (1995); Lawrence R. Liebesman &
Steven G. Davison, Takings of Wildlife Under the Endangered Species Act after Babbitt v.
Sweet Home Chapter of Communities for a Great Oregon, 5 U. B
ALT
. J. E
NVTL
. L. 137
(1995); Richard A. Epstein, Babbitt v Sweet Home Chapters of Oregon: The Law and Eco-
nomics of Habitat Preservation, 5 S
UP
. C
T
. E
CON
. R
EV
. 1 (1997); Fiona Powell, Defining
Harm Under the Endangered Species Act: Implications of Babbitt v. Sweet Home, 33 A
M
.
B
US
. L. J. 131 (1995); Patrick J. Beirne, Babbitt v. Sweet Home Chapter of Communities for a
Great Oregon: The Supreme Court Places the Endangered Species Act in “Harm’s” Way, 23 N.
K
Y
. L. R
EV
. 81 (1995); Steven G. Davison, The Aftermath of Sweet Home Chapter: Modifica-
tion of Wildlife Habitat as a Prohibited Taking in Violation of the Endangered Species Act, 27
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2011] Tzankova et al., Nitrogen Deposition 451
In the end, however, the Sweet Home decision has not made it much
easier to distinguish between the kinds of habitat modification that injure
protected wildlife sufficiently to qualify as harm and the kinds of habitat
modification that remain outside the scope of the section 9 take prohibition.
89
A clear and vivid illustration of the legal and regulatory ambiguity that con-
tinues to surround the reach of the harm prohibition can, for example, be
found in a recent ABA deskbook on the ESA.
90
Two adjacent chapters in
this authoritative legal volume offer appreciably different readings of the
Sweet Home decision, complete with diverging accounts of whether and how
Sweet Home defines or redefines the meaning of harm via habitat
modification.
In one chapter, Sean Skaggs
91
presents the Sweet Home decision as
strengthening, rather than circumscribing, the reach of section 9 protec-
tions.
92
He views the decision as an important part in a larger continuum of
broad judicial interpretation of harm. His analysis considers many of the
cases where courts found that listed wildlife was not harmed by habitat mod-
ification as cases of weak evidence of wildlife injury, rather than cases indi-
cating progressively stricter judicial standards for harm via habitat
modification. It includes both pre and postSweet Home cases such as
Morrill v. Lujan,
93
American Bald Eagle v. Bhatti,
94
and Hawksbill Sea Tur-
tle v. Federal Emergency Management Agency.
95
Skaggs also questions the idea that in a postSweet Home world, popu-
lation-level effects such as overall population declines of protected wild-
life that are attributable to habitat destruction are insufficient evidence of
harm; he essentially rejects the idea that individual animals must be shown
to be killed or tangibly injured by a habitat modification before the habitat
modification becomes a prohibited take.
96
W
M
. & M
ARY
E
NVTL
. L. & P
OL
Y
R
EV
. 541 (2003). What our analysis aims to emphasize is
the uncertainty that still remains even after Sweet Home regarding which kinds of habitat
modification can be considered prohibited harm and which cannot.
89
See, e.g., Davison, supra, note 88; Liebesman and Davison, supra note 88; Bean, supra
R
note 13; Fischman, supra note 79, at 68485 n.146 and accompanying text; Steven P. Quarles
R
& Thomas R. Lundquist, When Do Land Use Activities “Take” Listed Wildlife Under ESA
Section 9 and the “Harm” Regulation?, in E
NDANGERED
S
PECIES
A
CT
: L
AW
, P
OLICY
,
AND
P
ERSPECTIVES
, supra note 45, at 207; see also Amy L. Stein, State Fish Stocking Programs at
R
Risk: Takings Under the Endangered Species Act, 20 D
UKE
E
NVTL
. L. & P
OL
Y
F. 63 (2010).
90
E
NDANGERED
S
PECIES
A
CT
: L
AW
, P
OLICY
,
AND
P
ERSPECTIVES
, supra note 45.
91
Counselor to the Assistant Secretary for Fish and Wildlife and Parks, U.S. Department
of the Interior at the time of publication of his chapter in the ABA volume. Sean C. Skaggs,
Judicial Interpretation of Section 9 of the Endangered Species Act Before and After Sweet
Home: More of the Same, in E
NDANGERED
S
PECIES
A
CT
: L
AW
, P
OLICY
,
AND
P
ERSPECTIVES
,
supra note 45, at 253.
92
Id.
93
802 F. Supp. 424 (S.D. Ala. 1992).
94
9 F.3d 163 (1st Cir. 1993).
95
11 F. Supp. 2d 529 (D. V.I. 1998).
96
Skaggs, supra note 91, at 276.
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452 Harvard Environmental Law Review [Vol. 35
By contrast, in the second chapter, Steven Quarles and Thomsas R.
Lundquist
97
interpret Sweet Home as a decision that limits the scope of take
via habitat modification.
98
According to Quarles and Lundquist, to harm
listed wildlife means to (1) proximately cause (2) the death or tangible actual
injury to (3) an identifiable member of a listed wildlife species.
99
They spe-
cifically insist that a significant impairment of essential behavioral patterns
such as might often result from habitat modification or destruction that
displaces protected wildlife from traditional breeding, feeding, or sheltering
grounds cannot constitute wildlife injury in and of itself.
100
They also
insist on a fairly direct link between a habitat-altering activity and species
injury before an activity is to be scrutinized as prohibited take.
101
Yet contrary to the view proffered by Quarles and Lundquist, the Sweet
Home majority looks to the legislative history of the ESA as an indication of
congressional intent that “take” should “apply broadly to cover indirect as
well as purposeful actions.”
102
Especially significant for the present discus-
sion, Justice O’Connor’s concurrence also states that “Proximate causation
depends to a great extent on considerations of the fairness of imposing lia-
bility for remote consequences.”
103
Finally, and very critical for the question
at the center of this Article, the Sweet Home majority opinion concludes with
a note on the difficulty of measuring the vastly varied array of public and
private activities against the harm prohibitions of section 9, commenting on
the wisdom of leaving such measuring to the agencies and the courts:
The proper interpretation of a term such as “harm” involves a
complex policy choice. . . . In the elaboration and enforcement of
the ESA, the Secretary and all persons who must comply with the
law will confront difficult questions of proximity and degree; for,
97
Both with the Washington, DC, law firm of Crowell & Moring LLP at the time of
publication of their chapter in the ABA volume, Quarles and Lundquist represented the land-
owner interests in Sweet Home, as well as in a number of the cases discussed in their chapter.
Quarles & Lundquist, supra note 89.
R
98
Id. at 208. In constructing this argument, Quarles and Lundquist rely on the preamble
of the 1981 FWS regulation that defines “harm” and on the government’s testimony during the
Sweet Home trial. Id. at 21517. They do, however, recognize and lament the fact that the
Sweet Home decision has failed to produce true consistency and uniformity to the application
of section 9 in actual practice. Id. at 208. The way that such different reads of the Sweet
Home ruling can remain simultaneously plausible is through ongoing differences among legal
scholars and practitioners regarding the parts of the Sweet Home opinion that are properly seen
as binding precedent and those that should be regarded as mere dicta. It is partly by consider-
ing a much greater portion of the majority opinion as binding precedent than Skaggs does that
Quarles and Lundquist arrive at their view of Sweet Home as a decision that circumscribes the
meaning of “take” via habitat modification in several important ways.
99
Id. at 21415.
100
Id. at 216.
101
Id. at 23738.
102
Sweet Home, 515 U.S. at 704 (emphasis added). Justice O’Connor’s concurrence does
not exclude indirect causation either it only excludes causal arguments which fall under the
categories of the unforeseeable and “the bizarre,” as represented in extreme cases like Pal-
sgraf v. Long Island R. Co., 162 N.E. 99 (N.Y. 1928).
103
Sweet Home, 515 U.S. at 713 (emphasis added).
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2011] Tzankova et al., Nitrogen Deposition 453
as all recognize, the Act encompasses a vast range of economic
and social enterprises and endeavors. These questions must be ad-
dressed in the usual course of the law, through case-by-case reso-
lution and adjudication.
104
How then should the checkerspot case be situated within the still-uncer-
tain legal terrain of take via habitat modification? One way to answer this
question is to start with narrower interpretations of the Sweet Home opinion
and of harm through habitat modification as the benchmark for evaluating
the plausibility and robustness of a possible case for nitrogen deposition as a
take of threatened checkerspots. This is the approach taken in the next sub-
section. It is important to keep in mind, however, the fact that the Supreme
Court has ultimately left decisions to lower courts as to whether or not a
particular instance of habitat modification constitutes harm and a prohibited
take. Thus, not all courts will be applying the most stringent legal standard
possible for harm through habitat modification, a standard which could be
difficult or impossible to meet through existing or obtainable scientific
data.
105
C. Situating Nitrogen Deposition in the Uncertain Legal Terrain
of Take via Habitat Modification
Three principal challenges can be expected to arise in response to a
legal claim that nitrogen emissions and the resulting nitrogen deposition
constitute a prohibited “take” of threatened checkerspots. First, nitrogen
emissions and the resulting nitrogen deposition may not be considered a sig-
nificant enough cause of the invasion-driven modification of checkerspot
serpentine habitat, and checkerspot harm resulting from nitrogen-driven
habitat alteration may not be seen as sufficiently foreseeable to be legally
actionable. In other words, it is unclear whether a court would see nitrogen
emissions as a proximate cause of checkerspot harm given the nature and
extent of their contribution to the degradation of checkerspot habitat. Sec-
ond, even if nitrogen emissions and the resulting nitrogen deposition are
established as a significant enough factor in the degradation of the checker-
spot’s remaining serpentine habitats, courts or agencies may not find that
such nitrogen-related habitat modification has been conclusively shown to
result in the death of individual checkerspots, or in injury to individual
checkerspots sufficient to constitute harm, and thus constitute a prohibited
take. Third, the presumably offending nitrogen deposition results from the
actions of a large number of fairly small emitters. Therefore the individual
contribution of each emitter to the habitat modification is fairly small. Even
if nitrogen emissions are shown to be the proximate cause of harm to the
checkerspot, it might not be possible to establish liability in this context,
104
Id. at 708.
105
See, e.g., Robert L. Fischman, The Divides of Environmental Law and the Problem
of Harm in the Endangered Species Act, 83 I
ND
. L.J. 661, 68792 (2008).
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454 Harvard Environmental Law Review [Vol. 35
given that determining the contribution of individual emitters to the ultimate
species injury may be difficult, and given that many of the individual contri-
butions that cumulate to alter checkerspot habitat may by themselves be con-
sidered too small to be a significant cause of the resulting harm.
The first potential challenge to a claim of nitrogen emissions and depo-
sition as a prohibited take of checkerspots is largely left outside the present
discussion because it hinges on an empirical question beyond the scope of
this Article. An ongoing ecological investigation is working to quantify
with much greater precision the already observed relationship between nitro-
gen emissions, nitrogen deposition, non-native grass invasion, and changes
in native plant communities.
106
As a result, this question may be resolved in
the short to medium term. For the purposes of the current discussion, we
assume that such future research will further confirm the trends and relation-
ships observed so far that it will more solidly establish the significance of
emissions-origin nitrogen deposition as a key source of detrimental altera-
tion of the checkerspot’s only remaining habitats. This assumption is reason-
able based on evidence obtained so far.
107
This prospective view is also
warranted for reasons beyond the particulars of the checkerspot case because
it is often the case in environmental and resource policy that the emergence
of fairly clear and conclusive scientific understanding outpaces the develop-
ment of commensurate conservation policy action.
Admittedly, however, posing the question in this way constitutes a con-
siderable oversimplification of the actual challenges involved in bringing the
ESA to the aid of imperiled species in general, and the nitrogen-afflicted
checkerspot in particular. The above framing of the issue is an oversimplifi-
cation because, when it comes to deploying ESA protections against habitat-
related threats to listed species, the arguably most significant obstacle comes
from the fact that the ESA may set a legal standard for harm that requires
more certainty than ecological research can actually produce. This legal
standard may be quite difficult to meet even in cases where ecological evi-
dence clearly points to listed wildlife being harmed by changes to its
habitat.
108
Still, it is an oversimplification that we largely accept for the pur-
poses of the present discussion.
106
The following studies are currently in progress: Dena M. Vallano et al., Historical
Reconstruction of Anthropogenic N Inputs into a Bay Area Serpentine Ecosystem Using Tree
Ring ¨a15N Analysis (publication expected May 2011); Jae Pasari et al., Understanding the
Relative Importance of Changing Soil N and Other Soil Characteristics to Native and Exotic
Plant Species Composition in Serpentine Grasslands (results expected 2010); Paul C. Selmants
et al., Influence of Atmospheric Nitrogen Dioxide (NO
2
) and Ammonia (NH
3
) on Plant N Status
and Performance of Key Species in a Serpentine Grassland Ecosystem (publication expected
May 2011).
107
See generally Huenneke et al. supra note 6; Weiss, Cars, Cows, and Checkerspot But-
R
terflies, supra note 5; Erika S. Zavaleta et al., Grassland Responses to Three Years of Elevated
R
Temperature, CO
2
, Precipitation, and N Deposition, 73 E
COLOGICAL
M
ONOGRAPHS
585,
60001 (2003).
108
See Fischman, supra note 105, at 68490.
R
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2011] Tzankova et al., Nitrogen Deposition 455
The second potential challenge is also difficult to fully address within
the scope of this Article. In the case of the checkerspot, incontrovertible
links between nitrogen-driven habitat changes and the injury and death of
individual checkerspots the kinds of incontrovertible links demanded by
proponents of a strict legal standard are difficult to establish precisely
because the checkerspot is already so rare; too rare, for instance, for ecologi-
cal research to be able to compare and experimentally manipulate the rates
of larval survival in plots with and without added nitrogen deposition.
109
Narrow interpretations of the ESA’s harm prohibition therefore produce
situations that are unlikely to be resolved through further or better designed
ecological research or the continuous filling of remaining evidentiary and
knowledge gaps.
110
They present situations that may be resolvable only
through legal ingenuity and entrepreneurship, or through statutory and regu-
latory reform.
Promisingly for the potential of using the ESA to protect the checker-
spot, not all courts have applied as stringent of a legal standard for harm as
the strict interpreters discussed above,
111
and the Supreme Court majority in
Sweet Home leaves it to the lower courts to tackle the “difficult questions of
proximity and degree”
112
the difficult questions of when habitat modifica-
tion should be considered a prohibited take. In sum, then, both some further
ecological research and some legal ingenuity may be required to build a case
for nitrogen emissions (and nitrogen deposition) as a form of prohibited take
of checkerspots.
Assuming that a combination of legal ingenuity and ecological research
succeeds in establishing that emissions-origin nitrogen deposition is respon-
sible for causing prohibited harm to checkerspots, however, the third poten-
tial challenge still remains to be answered in order to build a robust section 9
case for the restriction of nitrogen emissions: namely, the question of who is
109
The ecological task of comparing larval mortalities in nitrogen-affected and unaffected
habitats is doubly compounded by the checkerspot’s rarity. Technically, there is the issue of
naturally high mortality rates among larvae in the pre-dormancy stage (mortality rates upwards
of 95 percent) and the difficulty of controlling for other factors if larval mortalities are com-
pared among distant sites experiencing different nitrogen deposition. See U.S. F
ISH
& W
ILD-
LIFE
S
ERV
., supra note 1, at 6. Practically, directly testing checkerspot population responses to
R
a manipulated nitrogen addition would require enormous areas to be intensively fertilized to
match the scale at which checkerspots move, which may further increase the risk of extinction.
See, e.g., P
UBLIC
D
RAFT
, S
ANTA
C
LARA
V
ALLEY
H
ABITAT
P
LAN
, supra note 25, app. D at 12.
R
Documenting foregone oviposition and other disruptions of checkerspot reproduction would
also pose significant and potentially insurmountable evidentiary challenges, if this is
indeed the evidence required by a court in order to show that checkerspot individuals were
harmed as a result of habitat modification.
110
This is in addition to the fact that perfect knowledge (or scientific certainty) is unrea-
sonable to expect in most science-based policy and regulatory decisions, including decisions
affecting threatened and endangered species. See, e.g., Fischman, supra note 105, at 661,
R
68492; Holly Doremus, Science and Controversy, in 2 T
HE
E
NDANGERED
S
PECIES
A
CT AT
T
HIRTY
, supra note 45, at 97, 10003.
111
See supra notes 98101 and accompanying text.
R
112
See Babbitt v. Sweet Home Chapter of Cmtys. for a Great Or., 515 U.S. 687, 708
(1995).
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 24 19-JUL-11 14:54
456 Harvard Environmental Law Review [Vol. 35
to be held responsible for the newly identified checkerspot take via nitrogen-
driven habitat modification. What remains are the key questions regarding
attributing liability and gauging the potential for effective injunctive relief to
prevent further harm to the checkerspot.
It is here that a comparison of the checkerspot case with the ESA case
against GHG emissions, and specifically with the ESA case against GHG
impacts on the threatened polar bear, offers particularly useful insight. This
comparison explicitly speaks to the plausibility of raising a take challenge
against nitrogen emissions and suggests a potentially fruitful strategy for
raising such a section 9 challenge. GHG emissions present a number of
significant challenges when it comes to attributing causation and liability for
harm to listed wildlife related to climate change. Still, a number of legal
scholars and practitioners have seen potential for raising a section 9 chal-
lenge against major US emitters of GHGs. Below, we argue that the chal-
lenges of attributing liability and causation in the nitrogen emissions/
checkerspot case are considerably more manageable than those in the GHG
case.
D. GHGs, Climate Change, and Polar Bears v. Nitrogen Emissions,
Nitrogen Deposition, and Checkerspots
In a context where growing numbers of species, including many imper-
iled species, are expected to become increasingly affected by the various
consequences of climate change,
113
the possibility of using the ESA to help
tackle GHG emissions has become the subject of recent discussion among
legal scholars and practitioners.
114
The polar bear a species of iconic
status that is particularly prone to habitat loss resulting from climate change
frequently appears as a “model organism” in such discussions.
The ESA case against GHG impacts on the threatened polar bear and
the ESA case against nitrogen impacts on the threatened checkerspot are
quite similar in a number of important ways. Polar bear populations have,
over time, been affected by the combined pressures of hunting, pollution, oil
and gas development, and climate change.
115
Increasingly, climate change
is recognized as the principal threat to the long-term survival of the spe-
113
See F. Stuart Chapin et al., Consequences of Changing Biodiversity, 405 N
ATURE
234,
234 (2000); John F. McLaughlin et al., Climate Change Hastens Population Extinctions, 99
P
ROC
. N
AT
L
. A
CAD
. S
CI
. 6070, 6070 (2002); Sala et al., supra note 10, at 1771; Chris D.
R
Thomas et al., Extinction Risk from Climate Change, 427 N
ATURE
145, 145 (2004); David
Tilman & Clarence Lehman, Human-Caused Environmental Change: Impacts on Plant Diver-
sity and Evolution, 98 P
ROC
. N
AT
L
. A
CAD
. S
CI
. 5433, 5433 (2001).
114
See articles cited supra note 15.
R
115
See Endangered and Threatened Wildlife and Plants; Determination of Threatened Sta-
tus for the Polar Bear (Ursus maritimus) Throughout Its Range, 73 Fed. Reg. 28,212, 28,212
(May 15, 2008); E
UGENE
H. B
UCK ET AL
., C
ONG
. R
ESEARCH
S
ERV
., RL 33941, P
OLAR
B
EARS
:
P
ROPOSED
L
ISTING UNDER THE
E
NDANGERED
S
PECIES
A
CT
4 (2007), available at http://www.
fas.org/sgp/crs/misc/RL33941.pdf; S
COTT
S
CHLIEBE ET AL
., U.S. F
ISH
& W
ILDLIFE
S
ERV
.,
R
ANGE
-W
IDE
S
TATUS
R
EVIEW OF THE
P
OLAR
B
EAR
(Ursus maritimus) 10809 (2006) (discuss-
ing effect of hunting on polar bear populations); Ian Stirling, Polar Bears and Oil: Ecological
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 25 19-JUL-11 14:54
2011] Tzankova et al., Nitrogen Deposition 457
cies.
116
On May 15, 2008, the FWS listed the polar bear as threatened.
117
The listing, which followed a petition and subsequent litigation,
118
was based
on concerns over the loss of sea ice habitat driven by climate change.
119
The
bears depend on sea ice for hunting, resting, mating, seasonal movements,
and travel to terrestrial denning areas.
120
Both the polar bear and the checkerspot case involve a dynamic of
harm by remote emissions which injure threatened wildlife through a com-
plex chain of causation that involves significant alterations of habitat and
consequent interference with essential behavioral patterns such as feeding,
breeding, and sheltering. Moreover, from an ESA section 9 perspective, the
polar bear case presents the same types of evidentiary challenges as the
checkerspot case when it comes to linking remote emissions to the harm
experienced by the protected wildlife.
121
The challenges of attributing re-
Perspectives, in S
EA
M
AMMALS AND
O
IL
: C
ONFRONTING THE
R
ISKS
, 223, 22830 (Joseph R.
Geraci & David J. St. Aubin, eds., 1990).
116
See A
RCTIC
C
LIMATE
I
MPACT
A
SSESSMENT
(ACIA), I
MPACTS OF A
W
ARMING
C
LIMATE
:
A
RCTIC
C
LIMATE
I
MPACT
A
SSESSMENT
58 (2004), available at http://amap.no/acia/; M
ELTZ
,
supra note 15, at 2; S
CHLIEBE ET AL
., supra note 115, at 72; U.S. G
EOLOGICAL
S
URVEY
, E
XEC-
R
UTIVE
S
UMMARY
, USGS S
CIENCE TO
I
NFORM
U.S. F
ISH
& W
ILDLIFE
S
ERVICE
D
ECISION
M
AK-
ING ON
P
OLAR
B
EARS
2 (2007), available at http://www.usgs.gov/newsroom/special/polar_
bears/; Andrew E. Derocher, Nicholas J. Lunn & Ian Stirling, Polar Bears in a Warming
Climate, 44 I
NTEGRATIVE
& C
OMP
. B
IOLOGY
163, 163 (2004).
117
See Endangered and Threatened Wildlife and Plants; Determination of Threatened Sta-
tus for the Polar Bear (Ursus maritimus) Throughout Its Range, 73 Fed. Reg. 28,212 (May 15,
2008).
118
Ctr. for Biological Diversity, Petition to List the Polar Bear (Ursus maritimus) as a
Threatened Species Under the Endangered Species Act (February 16, 2005), available at http:/
/www.biologicaldiversity.org/species/mammals/polar_bear/pdfs/15976_7338.pdf. For details
on the litigation that followed the initial petition, see B
UCK ET AL
., supra note 115, at 8.
R
119
The decision to list the bear was justified by loss of sea ice habitat, and the administra-
tion relied on scientific research pointing to climate change as the cause of sea ice loss to make
this case. Ironically, the listing makes absolutely no mention of climate change as the driver of
habitat loss and threats to the polar bear. See Endangered and Threatened Wildlife and Plants;
Determination of Threatened Status for the Polar Bear (Ursus maritimus) Throughout Its
Range, 73 Fed. Reg. 28,21228,303; Brendan R. Cummings & Kassie R. Siegel, Ursus mari-
timus: Polar Bears on Thin Ice, 22 N
AT
. R
ESOURCES
& E
NV
T
3, 3 (2007).
120
Ian Stirling & Andrew E. Derocher, Possible Impacts of Climatic Warming on Polar
Bears, 46 A
RCTIC
240, 241 (1993); Steven C. Amstrup, Polar Bear (Ursus maritimus), in
W
ILD
M
AMMALS OF
N
ORTH
A
MERICA
: B
IOLOGY
, M
ANAGEMENT
,
AND
C
ONSERVATION
587,
59296 (George A. Feldhamer et al. eds., 2003). At the same time as it impairs food access
and diminishes food availability, for example, decline in sea ice habitat caused by climate
change increases the bears’ energy requirements, as they travel through fragmented sea ice and
open water. See, e.g., Derocher et al., supra note 116, at 167. Unsurprisingly, reduced ice
R
presence has been related to declines in polar bear physical condition and reproduction. See
S
CHLIEBE ET AL
., supra note 115, at 74. Leading polar bear researchers, as well as recent
R
research led by the USGS, have established the seriousness of extinction threats from climate
change, concluding that projected sea ice declines should cause the loss of about two thirds of
the world’s polar bear population by mid-century. See U.S. G
EOLOGICAL
S
URVEY
, supra note
116, at 2.
R
121
Polar bear injuries stemming from sea ice loss-related changes in breeding, feeding,
and sheltering patterns have yet to be documented with a level of certainty that would satisfy
narrow interpreters of harm via habitat modification. It is similarly difficult to conclusively
attribute the observed deaths of four polar bears who drowned in trying to reach increasingly
distant sea ice to the growing concentrations of GHGs in the atmosphere. See Charles Monnett
& Jeffrey S. Gleason, Observations of Mortality Associated with Extended Open-Water Swim-
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458 Harvard Environmental Law Review [Vol. 35
sponsibility (and liability) for emissions-triggered habitat modification, how-
ever, turn out to be much more significant in the polar bear case than in the
checkerspot case.
First, it is difficult to establish that any of the individual GHG sources
located within the jurisdictional reach of the ESA contribute to climate
change significantly enough to cause actual, detectable changes in the polar
bear’s sea ice habitat. Thus, even if we know that climate change is the
cumulative effect of the GHGs from different emitters climate change
that has been linked to polar bear injuries and deaths the significance of
individual United States emitters’ contributions to these injuries remains dif-
ficult to quantify.
122
This difficulty is further compounded by the long residence times of
GHGs in the atmosphere. Such long residence times make it possible for
any GHG emitters that find themselves as defendants in a polar bear take
case to argue that past rather than present emissions are in fact responsible
for the presently experienced advances in climate change and their impacts
on listed polar bears. Long GHG residence times also make it even harder to
disaggregate the contribution of individual GHG emitters to any observed
polar bear injuries.
123
Finally, it is prohibitively difficult to trace the path of emissions from a
specific, individual source through the atmosphere. Together with long resi-
dence times, this knowledge deficiency makes the attribution of any liability
for harming protected wildlife a particularly fraught enterprise. To para-
phrase Matthew Gerhart’s helpful practical grounding of these issues, it will
be very hard for a plaintiff to demonstrate that a coal plant in Ohio is violat-
ing section 9 because it releases carbon dioxide, which contributes to global
warming, which causes disappearance of the sea ice, which has caused polar
bears to drown in open water.
124
Despite these difficulties in showing causation and attributing liability
for climate change-triggered harm to polar bears, the Bush Administration
viewed a legal challenge accusing major GHG emitters of taking polar bears
in violation of section 9 of the ESA as plausible enough to warrant the pro-
mulgation of a rule that essentially exempts GHG emitting activities from
the take provisions of ESA section 9.
125
In the context of the broader policy
battle to reduce GHG emissions, legal scholars and practitioners have also
seen a section 9 take challenge as plausible enough to caution against the
launching of such a challenge, raising concerns about the ultimate inability
ming by Polar Bears in the Alaskan Beaufort Sea, 29 P
OLAR
B
IOLOGY
681, 681 (2006). For
more details on the yet to be filled evidentiary gaps in a polar bear taking case against GHG
emitters, see, for example Gerhart, supra note 15, 173.
R
122
See Gerhart, supra note 15, at 198; M
ELTZ
, supra note 15, at 3.
R
123
See Gerhart, supra note 15, at 198.
R
124
See id., at 169; see also Ruhl, Endangered Species Act, supra note 14, at 284 n.44.
R
125
Specifically, the special rule states that “[n]one of the prohibitions of § 17.31 of this
part apply to any taking of polar bears that is incidental to, but not the purpose of, carrying out
an otherwise lawful activity within the United States, except for any incidental taking caused
by activities in areas . . . within the current range of the polar bear.” 50 C.F.R. § 17.40(q)(4).
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 27 19-JUL-11 14:54
2011] Tzankova et al., Nitrogen Deposition 459
of the ESA to meaningfully address the GHG problem,
126
as well as about
the potential of any attempted extension of the act to backfire politically.
127
In comparison to the GHG example, responsibility for offending nitro-
gen emissions in the checkerspot case should be easier to attribute. This is
partly because the dynamics of nitrogen deposition are much simpler than
the dynamics of GHG-driven climate change. Long-distance transport of
biologically reactive nitrogen is negligible and residence times for nitrogen
in the atmosphere are relatively short.
128
Furthermore, nitrogen deposition is
generally traceable to a range of emitters on a regional scale.
129
That is, the
population of nitrogen emitters responsible for a particular harmful instance
of nitrogen deposition is much more geographically circumscribed, and as a
result, these emitters are much easier to define.
Most importantly, attributing responsibility for an emissions-triggered
take is easier in the checkerspot case because tracing the nitrogen contribu-
tions of individual major emitters and assessing their share of responsibility
for the alteration of checkerspot habitat should not be necessary to build a
robust take case against nitrogen emissions. The regulation of nitrogen
emissions under existing federal and state air quality statutes arguably means
that a plaintiff in a section 9 case aimed at stopping nitrogen-related take of
checkerspots would not need to target individual stationary and mobile emit-
ters. Rather, following the precedent established by cases such as Defenders
of Wildlife v. EPA
130
and Strahan v. Coxe,
131
a plaintiff could target the fed-
eral and state agencies that have discretionary authority over setting ambient
air quality standards for emissions of reactive nitrogen compounds and over
the regulation and permitting of nitrogen emissions from stationary and mo-
bile sources. It is arguably those agencies, rather than individual emitters,
that are ultimately responsible for the overall amount of regional nitrogen
emissions, and so are responsible for the overall amount of nitrogen deposi-
tion and resultant harm to the checkerspot.
132
126
Ruhl, Endangered Species Act, supra note 14, at 289; Baur, supra note 14, at 10747.
R
127
Ruhl, Climate Change, supra note 13, at 41, 60.
R
128
See, e.g., Fenn et al., supra note 25, at 39495
R
129
See, e.g., id. (noting that nitrogen can be traced via atmospheric modeling and regional
air pollutant monitoring).
130
882 F.2d 1294 (8th Cir. 1989).
131
127 F.3d 155 (1st Cir. 1997).
132
Combustion-origin NH
3
emissions from stationary and mobile sources remain unregu-
lated, making it harder to apply the same type of ESA leverage as for NO
x
. See Bishop et al.,
supra note 39, at 3616. NH
3
(and other nitrogen as well as non-nitrogen emissions) from large
R
animal feeding operations are, however, increasingly coming under (arguably long overdue)
CAA scrutiny for future regulation. See, e.g., R.W. Pinder et al., Ammonia Emission Controls
as a Cost-Effective Strategy for Reducing Atmospheric Particulate Matter in the Eastern
United States, 41 E
NVTL
. S
CI
. & T
ECH
. 380, 38485 (2007). The regulation of such agricul-
tural ammonia emissions has already begun in Idaho and in some of the most heavily impacted
air districts in California, such as the South Coast Air Quality Management District. See
C
LAUDIA
C
OPELAND
, C
ONG
. R
ESEARCH
S
ERV
., RL 32948, A
IR
Q
UALITY
I
SSUES AND
A
NIMAL
A
GRICULTURE
: A P
RIMER
1115 (2010), available at http://www.nationalaglawcenter.org/as-
sets/crs/RL32948.pdf; Jeff El-Hajj, Confined Animal Feeding Operations in California: Cur-
rent Regulatory Schemes and What Must Be Done to Improve Them, 15 H
ASTINGS
W.-N
W
. J.
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460 Harvard Environmental Law Review [Vol. 35
The precise apportionment of liability among EPA and the state regula-
tory agencies with parallel responsibilities for air quality standards and emis-
sion controls is beyond the scope of this Article. It is, however, important to
note that the extent of agency liability for harmful nitrogen emissions will
depend on the extent of discretionary authority that an agency has over rele-
vant standard-setting and emissions permitting decisions. For example, to
the extent that both CARB and EPA have discretionary authority to set Cali-
fornia air quality standards for NO
x
and other nitrogen emissions (such as
NH
3
) and to regulate mobile source emissions, each of the agencies could be
seen as responsible for the deposition impacts of nitrogen emissions on listed
species like the checkerspot.
133
Similarly, responsibility would extend to rel-
evant Air Quality Management Districts, such as the Bay Area Air Quality
Management District (“BAAQMD”), which is in charge of emissions per-
mitting in the region where most of the nitrogen emissions impacting check-
erspot habitat and affecting the threatened checkerspot originate. On the one
hand, to the extent that the BAAQMD has discretionary authority over the
permitting of individual stationary source emitters within its jurisdiction, it
can and arguably should be held responsible for the listed species
impacts of the nitrogen emissions it issues permits for.
134
On the other hand,
to the extent that many state-level emission control activities, for both mo-
bile and stationary sources, are driven by the desire to comply with discre-
tionary federal EPA ambient air quality standards for NOx, and to the extent
that the nitrogen-driven modification of checkerspot habitat occurred in the
context of long-term compliance with EPA’s ambient standard, a considera-
ble amount of the responsibility for a checkerspot take via nitrogen-driven
habitat modification may ultimately rest with EPA. Liability apportionment
between responsible regulatory agencies can prove quite complex in
practice.
E
NVTL
. L. & P
OL
Y
349, 36265 (2009); see also Sarah C. Wilson, Hogwash! Why Industrial
Animal Agriculture is Not Beyond the Scope of Clean Air Act Regulation, 24 P
ACE
E
NVTL
. L.
R
EV
. 439, 45966 (2007); S. Coast Air Quality Mgmt. Dist., Rule 1127, Emission Reductions
from Livestock Waste (2004), available at http://www.aqmd.gov/rules/reg/reg11/r1127.pdf.
Further, starting to regulate both combustion- and livestock- source NH
3
under the CAA is
being discussed as a way to control the formation of particulate matter. NH
3
is a precursor to
the formation of fine particulates (“PM
2.5
”), which EPA already regulates as a criteria pollu-
tant, through the imposition of a National Ambient Air Quality Standard a standard which
many areas in the country are currently having trouble attaining. See Pinder et al., supra, at
380.
133
For details on (1) the division of federal-state responsibilities for air quality control in
general, and mobile source emissions regulation in particular, and (2) the extent of discretion-
ary authority that EPA and CARB have over the setting of mobile source standards, see, for
example, N
AT
L
R
ESEARCH
C
OUNCIL
, S
TATE AND
F
EDERAL
S
TANDARDS FOR
M
OBILE
S
OURCE
E
MISSIONS
65113 (2006).
134
For further details on the workings of cooperative federalism under the CAA, see infra
notes 157172, 196198 and accompanying text. See generally N
AT
L
R
ESEARCH
C
OUNCIL
,
R
supra note 133, at 65113; John P. Dwyer, Environmental Federalism: The Practice of Feder-
R
alism Under The Clean Air Act, 54 M
D
. L. R
EV
. 1183 (1995); Arnold W. Reitze, Jr., Air
Quality Protection Using State Implementation Plans Thirty-Seven Years of Increasing
Complexity, 15 V
ILL
. E
NVTL
. L.J. 209 (2004).
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2011] Tzankova et al., Nitrogen Deposition 461
Another critical difference between the GHG/polar bear case and the
nitrogen/checkerspot case which makes the checkerspot easier to regulate is
the regulatory situation of nitrogen as opposed to GHGs. Namely, even if
GHG emissions were federally regulated by a single agency, this agency
would still not have power over all of the emitters responsible for climate
change and the climate-change-driven destruction of polar bear habitat be-
cause so many of these emitters are located outside the United States. And
even if responsibility for offending GHG emissions could be attributed to a
single regulatory agency, rather than the vast number of individual GHG
emitters, the viability of a take challenge against the agency would still de-
pend on the ability to show that a change in the agency’s regulatory actions
could appreciably reduce the extent or rate of climate change. This is a
significant burden of proof, even if meeting it has arguably become more
plausible in the aftermath of Massachusetts v. EPA.
135
No such problems are
foreseeable with nitrogen, where emissions are deposited regionally, and are
thus largely within the control of federal and state agencies. In sum, it
should be considerably easier (and much more practicable) to establish both
causation and liability in the checkerspot case.
In evaluating prospects of a take challenge against agencies responsible
for the harmful nitrogen deposition by virtue of their responsibilities for reg-
ulating nitrogen emissions, it is also important to apply the fairness standard
advanced by Justice O’Connor’s concurring opinion in Sweet Home.
136
To
the extent that decisions about proximate causation are determined by the
fairness of imposing liability for remote consequences, it is useful to con-
sider whether it is fair and reasonable to hold air quality or emissions control
agencies (at the federal and state level) liable for the serpentine habitat de-
cline and checkerspot injuries occurring as a result of nitrogen deposition.
The comparison with the GHG/polar bear case is once again particu-
larly helpful in approaching this question. For example, using the ESA to
leverage GHG reductions by going after individual large emitters poses
some significant questions about fairness, especially since such use of the
ESA is clearly strategic. ESA litigation against GHGs can be seen as a way
to create annoyance and regulatory uncertainty for a significant number of
large emitters annoyance and uncertainty that might just become large
enough to make a national climate/GHG policy seem preferable to the alter-
native, thereby inducing major emitters to support a uniform policy. Under
this view, ESA litigation against GHG emitters is essentially a way of nudg-
ing US climate policy forward, rather than an actual, practical way of stop-
ping harm to listed species.
135
549 U.S. 497 (2007). For a more detailed discussion on the relevance of Massachu-
setts v. EPA to the case of leveraging the ESA for control of GHG emissions, see M
ELTZ
, supra
note 15, at 3; Gerhart, supra note 15, at 189; see also Ruhl, Climate Change, supra note 13, at
R
911, 4546.
136
Babbitt v. Sweet Home Chapter of Cmtys. for a Great Or., 515 U.S. 687, 713 (1995)
(O’Connor, J., concurring).
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462 Harvard Environmental Law Review [Vol. 35
Conversely, leveraging the ESA to get federal and state agencies to
better consider the ecological implications of their air quality and emissions
regulations seems hardly unfair, especially when we take into account the
fact that such agencies already have explicit mandates to protect ecosystems
as well as human health in making their regulatory decisions.
137
V. T
HE
S
ECTION
7 J
EOPARDY AND
C
RITICAL
H
ABITAT
S
TANDARDS AND
EPA R
EGULATION OF
N
ITROGEN
E
MISSIONS
U
NDER THE
CAA
The possibility that nitrogen deposition constitutes a prohibited take of
checkerspots has implications for the implementation of Section 7 of the
ESA as well. Section 7 requires each federal agency to ensure that its ac-
tions do not jeopardize the continued existence of any threatened or endan-
gered species or adversely modify the designated critical habitat of such
species.
138
Section 7 adds an affirmative species protection duty to the pri-
mary mandates and overall obligations of federal agencies.
The FWS regulations define jeopardizing the continued existence of a
listed species to mean engaging in an action that reasonably would be ex-
pected to directly or indirectly reduce the likelihood of survival and recovery
of a listed species in the wild.
139
An agency action is, in turn, considered
destruction or adverse modification of critical habitat if it produces a “direct
or indirect alteration that appreciably diminishes the value of critical habitat
for both the survival and recovery of a listed species.”
140
Agency actions covered by the section 7 jeopardy and critical habitat
provisions are defined broadly to include “all activities or programs of any
kind authorized, funded, or carried out, in whole or in part, by Federal agen-
cies.”
141
Importantly, then, federal agency activities covered under the sec-
tion 7 jeopardy prohibition include not only projects directly conducted by
the agencies themselves, like the construction of highways, seawalls, and
water works, or the operation of a federal facility, but also any regulatory,
permitting, licensing, leasing, contracting, grant-making, or other activities
that can result in modifications of “land, water, or air.”
142
137
42 U.S.C. §§ 7409(b), 7602(h) (2006).
138
16 U.S.C. § 1536(a)(2) (2006). After Tennessee Valley Authority v. Hill, 437 U.S. 153
(1978), Congress amended the ESA to allow agencies to seek exemption from the jeopardy
prohibition through the Endangered Species Committee, but, in reality, appeals to the Commit-
tee for such exemptions are exceedingly rare. See Patrick Parenteau, The Exemption Process
and the “God Squad”, in E
NDANGERED
S
PECIES
A
CT
: L
AW
, P
OLICY
,
AND
P
ERSPECTIVES
, supra
note 45, at 132, 143.
139
50 C.F.R. § 402.02 (2010).
140
Id. (emphasis added).
141
Id.
142
Id. Courts have also interpreted the meaning of agency actions quite broadly for the
purposes of section 7 consultation and jeopardy avoidance requirements. See Marilyn Averill,
Protecting Species Through Interagency Cooperation, in E
NDANGERED
S
PECIES
A
CT
: L
AW
,
P
OLICY
,
AND
P
ERSPECTIVES
, supra note 45, at 9091.
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 31 19-JUL-11 14:54
2011] Tzankova et al., Nitrogen Deposition 463
Federal agencies are expected to ensure that none of their numerous
actions would jeopardize the continued existence of a listed species or ad-
versely modify its designated critical habitat through consultation with the
FWS or NMFS.
143
Under section 7, then, a federal agency embarking on a
regulatory action is required to consider the effects of such action on any
ESA-listed species within the action area.
144
If the agency, in informal con-
sultation with the FWS or NMFS, determines that its intended action may
adversely affect a listed species or critical habitat, then the agency is re-
quired to enter into a formal consultation with the FWS or NMFS. Formal
consultation culminates with a Biological Opinion (“BO”) in which FWS
and NMFS state their findings as to the effects of the proposed action on
listed species and their critical habitat. In reality, jeopardy findings are quite
rare, and projects being stopped because of listed species jeopardy are rarer
still.
145
In the infrequent occasions when the FWS does conclude that an
agency action as proposed will result in jeopardy to a listed species, it usu-
ally offers “reasonable and prudent alternatives” which the agency can then
incorporate into its project planning and execution in order to avoid such
jeopardy.
146
Some legal scholars have described section 7 as “the most robust com-
mand-and-control weapon in the arsenal of environmental law”
147
and see
the outcomes of section 7 consultations as “exceptionally dispositive of fed-
143
50 C.F.R. § 402.01(b) (2010).
144
For details on the consultation requirements and process, see U.S. F
ISH
& W
ILDLIFE
S
ERV
. & N
AT
L
M
ARINE
F
ISHERIES
S
ERV
., E
NDANGERED
S
PECIES
C
ONSULTATION
H
ANDBOOK
:
P
ROCEDURES FOR
C
ONDUCTING
C
ONSULTATION AND
C
ONFERENCE
A
CTIVITIES
U
NDER
S
ECTION
7
OF THE
E
NDANGERED
S
PECIES
A
CT
(1998). For specific discussion of how “action area” can
be interpreted in a context of remote, emissions-origin threats, see Gerhart, supra note 15, at
R
17377.
145
See, e.g., U.S. G
OV
T
A
CCOUNTABILITY
O
FFICE
, GAO-92-131BR, Endangered Species
Act: Types and Number of Implementing Actions (1992); U.S. G
OV
T
A
CCOUNTABILITY
O
F-
FICE
, GAO-04-93, E
NDANGERED
S
PECIES
: M
ORE
F
EDERAL
M
ANAGEMENT
A
TTENTION
I
S
N
EEDED TO
I
MPROVE THE
C
ONSULTATION
P
ROCESS
7, 49, 50, 5657 (2004); see also Christo-
pher E. Williams, The Cost of Continued Existence: Assessing the Impacts of Section 7 on
Federal Agencies, Private Actors, and Endangered Species, in E
NDANGERED
S
PECIES
A
CT
:
L
AW
, P
OLICY
,
AND
P
ERSPECTIVES
, supra note 45, at 179; Oliver A. Houck, The Endangered
Species Act and Its Implementation by the U.S. Departments of Interior and Commerce, 64 U.
C
OLO
. L. R
EV
. 277, 301, 311, 31718 (1993).
146
If the agency action subject to section 7 consultation is expected to result in some take
of listed wildlife, the FWS BO may include an incidental take statement, which insulates the
agency (or the private applicant for an agency permit) from liability under section 9 by for-
mally permitting a certain specified and limited amount of species take. Incidental take
statements are only issued as part of a BO if the take resulting from the activities of federal
agencies or their permittees is not causing jeopardy to the affected species, and if they are
accompanied by the specification of reasonable and prudent measures to minimize the impacts
of agency (or permittee) actions on the listed species affected. What this also means, though,
is that if an agency such as EPA fails to conduct section 7 consultation for its regulatory
actions, it is also failing to secure an incidental take permit; this leaves the agency vulnerable
to section 9 litigation should its regulatory actions result in direct or habitat related harm to
listed wildlife.
147
Laurence M. Bogert, The Endangered Species Act and Categorical Statutory Com-
mands after National Association of Homebuilders v. Defenders of Wildlife, 44 I
DAHO
L. R
EV
.
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464 Harvard Environmental Law Review [Vol. 35
eral (and, in certain circumstances, private) activity interfacing with species
listed under the ESA.”
148
A close look at the range of practical experience does not necessarily
bear out the “dispositive” notion,
149
but section 7 is nonetheless important.
Even if it seldom halts or changes federal projects and regulations,
150
it can
still force both federal agencies and applicants for federal permits to con-
sider the needs and well-being of listed species at the early stages of project
planning and regulatory action. It can thereby offer threatened and endan-
gered species an added level of protection.
151
A. Section 7 Requirements, Nitrogen Emissions, and Nitrogen Deposition
Section 7 focuses on the impacts of federal agency actions on both the
survival and recovery of listed species. Considering that the checkerspot is
about to be reclassified from threatened to endangered partly due to nitro-
gen-driven alterations of its habitat,
152
any federal agency action appreciably
contributing to nitrogen emissions that deposit on checkerspot habitat should
require section 7 scrutiny and consultation. In fact, given the mechanisms of
nitrogen impact on the checkerspot and its serpentine habitat, section 7 pro-
vides multiple triggers for scrutiny of federal actions that contribute to nitro-
gen emissions that deposit on checkerspot habitat.
First, showing that the habitat modifications triggered by nitrogen emis-
sions and the resultant nitrogen deposition reduce the likelihood of checker-
spot survival and recovery may turn out to be easier, in ecological terms,
than showing death or injury of identifiable checkerspot individuals. That is,
showing that nitrogen deposition causes jeopardy to the checkerspot may be
easier than showing that nitrogen deposition causes prohibited take of check-
erspots. Second, given the mounting ecological evidence that nitrogen emis-
sions (and resulting nitrogen deposition) are indirectly, but likely adversely,
modifying the serpentine grasslands that contain all of the designated critical
habitat of the checkerspot, the critical habitat provision of section 7 may
come into play.
153
Third, the nitrogen-driven modification of the checker-
543, 545 (2008) (citing W
ILLIAM
H. R
OGERS
J
R
., E
NVIRONMENTAL
L
AW
,§ 9.9, at 997 (2d ed.
1994)).
148
Id.
149
See, e.g., U.S. G
OV
T
A
CCOUNTABILITY
O
FFICE
, GAO-09-550, E
NDANGERED
S
PECIES
A
CT
: T
HE
U.S. F
ISH AND
W
ILDLIFE
S
ERVICE
H
AS
I
NCOMPLETE
I
NFORMATION ABOUT
E
FFECTS
ON
L
ISTED
S
PECIES FROM
S
ECTION
7 C
ONSULTATIONS
(2009); Mary Jane Angelo, The Killing
Fields: Reducing the Casualties in the Battle Between U.S. Species Protection Law and U.S.
Pesticide Law, 32 H
ARV
. E
NVTL
. L. R
EV
. 95 (2008); see also supra note 145 and accompany-
R
ing text.
150
See, e.g., Averill, supra note 142, at 10708; Williams, supra note 145, at 18487.
R
151
Averill, supra note 142, at 10708.
R
152
U.S. F
ISH
& W
ILDLIFE
S
ERV
., supra note 1, at 1315, 1619, 24, 2627.
R
153
Critical habitat for the checkerspot was proposed in 2000, Proposed Designation of
Critical Habitat for the Bay Checkerspot Butterfly, 65 Fed. Reg. 61,218 (proposed Oct. 16,
2000), designated in 2001, Final Determination of Critical Habitat for the Bay Checkerspot
Butterfly, 66 Fed. Reg. 21,449 (April 30, 2001), and revised in 2008, Designation of Critical
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2011] Tzankova et al., Nitrogen Deposition 465
spot’s serpentine habitat involves the disadvantaging and displacement of
native plant species in a context where several native plants are listed as
federally threatened or endangered.
154
Section 7 scrutiny may thus be trig-
gered by nitrogen effects on listed plants as well.
155
In this context, there are a considerable number and variety of federal
agency actions from highway funding and construction to the design and
promulgation of emissions trading schemes which may trigger section 7
consultation and require scrutiny against its jeopardy and critical habitat
standards. Indeed, any agency actions that regulate, authorize, fund, or oth-
erwise contribute to substantial emissions of nitrogen in the vicinity of
checkerspots and their nitrogen-sensitive serpentine habitats should trigger
section 7 scrutiny and consultation. The same obviously applies to agency
actions that contribute to nitrogen emissions in the vicinity of any nitrogen-
sensitive listed species or the nitrogen-sensitive critical habitats of listed
species.
In the rest of this section, we focus on federal air quality and emissions
control regulations, given their major significance in determining amounts of
nitrogen deposition on checkerspot habitat and beyond. Further, and equally
as important, adjusting federal emission controls and federal air quality stan-
dards in response to section 7 leverage from the ESA should be quite practi-
cable and indeed is arguably overdue. Given the tremendous complexity of
the regulatory regime created by the CAA, we selectively emphasize some
of the more relevant air quality and emission control actions across several
different scales of EPA regulatory intervention. At the same time, we en-
deavor to conduct our analysis in a way that allows for its extension to other
regulatory actions with a bearing on nitrogen emissions, including actions by
EPA and other federal agencies and actions under the CAA or other statutory
authorities.
156
Habitat for the Bay Checkerspot Butterfly, 73 Fed. Reg. 50,405 (Aug. 26, 2008) (codified at 50
C.F.R. pt. 17). For a summary of the litigation that prompted this revision and the changes in
checkerspot population between the two critical habitat designations, see Designation of Criti-
cal Habitat for the Bay Checkerspot Butterfly, 73 Fed. Reg. 50,405 (Aug. 26, 2008).
154
Current research on Bay Area serpentine grasslands is aimed at more rigorously quanti-
fying the effects of nitrogen deposition on native serpentine grassland plants, including listed
plant species. The latter include the Santa Clara Valley dudleya (Dudleya setchellii), Metcalf
Canyon jewelflower (Streptanthus albidus ssp. albidus), Tiburon Indian paintbrush (Castilleja
affinis ssp. neglecta), and coyote ceanothus (Ceanothus ferrisae). See Donald Mayall, Protect-
ing Coyote Ridge, 36 F
REMONTIA
: J. C
AL
. N
ATIVE
P
LANT
S
OC
Y
, 12, 15 (Winter 2008).
155
Unlike the take prohibition of section 9, which only shields listed wildlife, the jeopardy
and critical habitat prohibitions of section 7 are designed to protect both plant and wildlife
species listed as federally threatened or endangered. To the extent, of course, that the presence
of federally listed plant species in the checkerspot’s serpentine habitat provides a trigger for
scrutiny and perhaps modification of federal actions affecting nitrogen emissions (and nitrogen
deposition), the checkerspot can be expected to benefit. Further, any reductions in nitrogen
emissions and so ambient concentrations and nitrogen deposition, regardless of which particu-
lar ESA trigger brings them about, should be beneficial to serpentine ecosystems and other
nitrogen-sensitive systems or species in the affected region.
156
Other federal standard setting activities, such as the setting of CAFE standards, may
also call for section 7 scrutiny. NH
3
emissions, for example, are shown to have a strong
dependence on model year and vehicle-specific power (vehicle-specific power being a proxy
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466 Harvard Environmental Law Review [Vol. 35
The rest of this section considers the challenges and potential of apply-
ing section 7 requirements to several types of EPA regulatory actions with a
direct bearing on nitrogen emissions, ambient nitrogen concentrations, and
nitrogen deposition on checkerspot habitat, including: emissions permitting
for new sources, the setting of National Ambient Air Quality Standards
(“NAAQS”), and the approval of State Implementation Plans (“SIPs”).
This section further discusses the likelihood that such leveraging of the ESA
against the CAA could produce meaningful reductions in nitrogen emissions
and nitrogen deposition on checkerspot habitat.
B. Section 7 Consultation for EPA Regulations of
Nitrogen Emissions Under the CAA
In accord with the practice of cooperative federalism established under
the CAA, states make a number of important regulatory decisions regarding
the permitting and control of nitrogen emissions. For example, while EPA
controls emissions from new and modified sources through nationally uni-
form new source performance standards
157
and requirements for new source
review,
158
emissions limitations for existing sources are left to the states’ rel-
atively unfettered discretion.
159
In our case, California is also the only state
allowed by the CAA to set vehicle emission standards that exceed federal
standards.
160
States exercise much of their regulatory discretion in the context of air
quality planning, which culminates in a SIP that requires EPA approval
before it can enter into force.
161
EPA approval, in turn, depends on whether
the range of discretionary emission control, transportation control, vehicle
inspection and other measures stipulated in a SIP cumulate in a way that
variable for engine load that has been shown to be highly correlated with emissions). See
Bishop et al., supra note 39, at 3616, 3619.
R
157
42 U.S.C. § 7411 (2006).
158
42 U.S.C. §§ 74707479, §§ 75017515 (2006); see also A
RNOLD
W. R
EITZE
, A
IR
P
OLLUTION
C
ONTROL
L
AW
: C
OMPLIANCE AND
E
NFORCEMENT
17799 (2001); Bernard F. Haw-
kins, Jr. & Mary Ellen Ternes, The New Source Review Program: Prevention of Significant
Deterioration and Nonattainment New Source Review, in T
HE
C
LEAN
A
IR
A
CT
H
ANDBOOK
,
131, 13134 (Robert J. Martineau, Jr. & David P. Novello eds., 2d ed. 2001).
159
42 U.S.C. § 7410(a)(2) (2006). For a more detailed breakdown of federal and state
regulatory responsibilities under the CAA, see, for example, R
EITZE
, supra note 158, at 5659
R
and Dwyer, supra note 134, at 11901216.
R
160
42 U.S.C. § 7543 (2006). This occurred by virtue of a California pre-1967 vehicle
emission regulation being grandfathered into the predecessor of the CAA of 1970, the Air
Quality Act of 1967, Pub. L. No. 90-148, 81 Stat. 485. The waiver of federal preemption over
California vehicle emission standards has essentially stayed intact since then. For further de-
tails, see Michael J. Horowitz, Regulation of Mobile Sources: Motor Vehicles, Nonroad En-
gines, and Aircraft, in T
HE
C
LEAN
A
IR
A
CT
H
ANDBOOK
,supra note 158, at 323.
R
161
42 U.S.C. § 7410(a) (2006); see also Reitze, supra note 134, at 21112.
R
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 35 19-JUL-11 14:54
2011] Tzankova et al., Nitrogen Deposition 467
ensures attainment of NAAQS
162
for NO
2
163
standards that are set by the
EPA.
164
Within the CAA context of cooperative federalism, EPA retains author-
ity over a range of regulatory decisions that are significant in affecting nitro-
gen deposition on regional and national scales. These are the regulatory
decisions that invite section 7 scrutiny. Although state air quality and emis-
sion control regulations generally remain outside the reach of section 7’s
jeopardy and critical habitat requirements,
165
any state actions that affect ni-
trogen emissions and nitrogen deposition on checkerspot habitat can still fall
within section 9’s take prohibitions.
C. Section 7 Consultation for Permitting New Sources
of Nitrogen Emissions
There is already some limited precedent of section 7 consultation re-
garding the regulation of nitrogen emissions in the vicinity of nitrogen-sensi-
tive checkerspot habitat. This precedent was established in the context of
CAA permitting for a new natural gas power plant the Metcalf Energy
Center in South San Jose. The Metcalf Energy Center, as proposed, was
found to have NO
x
emission potential significant enough to qualify it as a
major new source under the CAA.
166
Together with the facility’s location in
the BAAQMD, a region with long-term attainment of NAAQS for NO
2
,
167
this meant that Metcalf’s developers had to obtain a CAA prevention of sig-
nificant deterioration permit (“PSD permit”) before construction of the
power plant could begin.
168
The BAAQMD, which handled the Metcalf permitting, is a state agency
acting as a delegate of EPA, and accordingly sets emission standards for
major new sources.
169
All PSD permits, including those issued by delegated
162
42 U.S.C. § 7410 (2006). See infra notes 178185 and accompanying text for details
R
on NAAQS and how they fit within the broader scheme of air quality and emissions control
under the CAA.
163
NAAQS are set by EPA for NO
2
and five other criteria pollutants. See id.
164
40 C.F.R. § 50.417 (2010). Section 116 of the CAA, however, allows states to adopt
more stringent air quality standards than the federal ones. See 42 U.S.C. § 7416 (2006).
165
This includes state regulations developed to implement CAA mandates as well as air
quality and nitrogen emission controls imposed through state law and regulation.
166
See 42 U.S.C. § 7479 (2006); see also Order Denying Review of Metcalf Energy
Center PSD Permit No. 99-AFC-3, PSD Appeal Nos. 01-07 and 01-08 (EPA Envtl. Appeals
Board Aug. 10, 2001), at 56; EPA, D
RAFT
N
EW
S
OURCE
R
EVIEW
W
ORKSHOP
M
ANUAL
A.22A.23 (1990).
167
But see infra note 186.
R
168
See 42 U.S.C. §§ 7470-79 (2006); see also U.S. F
ISH AND
W
ILDLIFE
S
ERV
., B
IOLOGI-
CAL
O
PINION IN THE
F
ORMAL
E
NDANGERED
S
PECIES
C
ONSULTATION ON THE
P
REVENTION OF
S
IGNIFICANT
D
ETERIORATION
P
ERMIT FOR THE
P
ROPOSED
M
ETCALF
E
NERGY
C
ENTER
, S
AN
J
OSE
, S
ANTA
C
LARA
C
OUNTY
, C
ALIFORNIA
13 (2001) [hereinafter M
ETCALF
BO].
169
BAAQMD is authorized to make PSD permitting decisions for new and modified sta-
tionary sources of air pollution in the San Francisco Bay area of California pursuant to a
delegation agreement with EPA Region IX. See 40 C.F.R. § 52.21(u) (2010); 56 Fed. Reg.
4,944 (Feb. 7, 1991); see also EPA, B
AY
A
REA
A
IR
Q
UALITY
M
ANAGEMENT
D
ISTRICT
A
GREE-
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 36 19-JUL-11 14:54
468 Harvard Environmental Law Review [Vol. 35
states, are considered by EPA to be federal actions for the purposes of ESA
section 7.
170
As a result, EPA initiated formal consultation with the FWS
regarding the effects of Metcalf’s PSD permit on the numerous listed species
found in the vicinity of the proposed power plant.
171
The effects of nitrogen
emissions on the checkerspot were considered as part of this consultation.
172
The resultant BO found that nitrogen (both NO
x
and NH
3
) discharged
from the power plant’s exhaust stacks would precipitate onto adjacent check-
erspot serpentine habitats.
173
However, the BO concluded that the emissions,
as limited by the permit, are not likely to jeopardize the continued existence
of the checkerspot or the listed serpentine plant species.
174
This is hardly a
surprise when we consider that the limitations of existing modeling capacity
prevent us from gauging the contribution of an individual nitrogen emitter to
the broader nitrogen-driven disruption of serpentine habitats and species.
175
What this ultimately means, though, is that section 7 consultation over indi-
vidual emission permits such as PSD permits for new facilities is
likely an inadequate tool when it comes to shielding the checkerspot or other
nitrogen-sensitive habitats and species from the threats of nitrogen emis-
sions. The regulatory action through which EPA affects checkerspot and its
serpentine habitat most is, arguably, the setting of NAAQS for NO
2
.
D. EPA’s NAAQS for NO
2
NAAQS are intended to protect public health and welfare.
176
They con-
sist of nationally uniform limits that EPA sets on the ambient concentrations
of the most ubiquitous and universally problematic air pollutants (also
known as criteria pollutants).
177
EPA designated and currently regulates six
criteria pollutants, including NO
2
, carbon monoxide, ozone, particulate mat-
ter, sulphur dioxide, and lead.
178
NAAQS for these six pollutants are to be
MENT FOR
L
IMITED
D
ELEGATION OF
A
UTHORITY TO
I
SSUE AND
M
ODIFY
P
REVENTION OF
S
IGNIF-
ICANT
D
ETERIORATION
P
ERMITS
S
UBJECT TO
40 C.F.R. 52.21 (2006).
170
See, e.g., EPA, supra note 166, at 5; Order Denying Review, PSD Appeal Nos. 1-07
R
and 1-08.
171
The consultation was initiated by EPA Region IX on March 24, 2000. See M
ETCALF
BO, supra note 168, at 1163.
R
172
See id. at 2324, 2627.
173
Id. at 78, 2324, 29.
174
Id. at 2728. Interestingly, the Metcalf BO includes the following statement as part of
its incidental take permitting: “Take in the form of harm of all bay checkerspot individuals due
to nitrogen deposition on 3,176 acres of habitat will become exempt from the prohibitions
described under section 9 of the Act for indirect impacts associated with the project.” Id. at 29.
This is notable because it suggests that the FWS has previously thought of nitrogen as a possi-
ble source of harm and a take of checkerspots.
175
See T
ONNESEN ET AL
., A
SSESSMENT OF
N
ITROGEN
D
EPOSITION
: M
ODELING AND
H
ABITAT
A
SSESSMENT
3 (2007).
176
42 U.S.C. § 7409(b) (2006).
177
42 U.S.C. §§ 740809 (2006); see also Richard E. Ayers & Mary Rose Kornreich,
Setting National Ambient Air Quality Standards, in T
HE
C
LEAN
A
IR
A
CT
H
ANDBOOK
,supra
note 158, at 13, 1314.
R
178
40 C.F.R. pt. 50 (2010); see also R
EITZE
, supra note 158, at 3349.
R
\\jciprod01\productn\H\HLE\35-2\HLE206.txt unknown Seq: 37 19-JUL-11 14:54
2011] Tzankova et al., Nitrogen Deposition 469
reviewed and updated every 5 years, although this has hardly ever been the
case in actual practice.
179
The level at which at which EPA sets NAAQS for NO
2
has immediate
significance in determining the overall levels of nitrogen emissions and dep-
osition on ecosystems nationwide. The CAA, in fact, explicitly acknowl-
edges the ecological implications of NAAQS by instructing EPA to set both
primary NAAQS that protect public health
180
and secondary NAAQS that
protect public welfare;
181
secondary NAAQS are defined to include protec-
tion from pollutant effects on water, soils, crops, vegetation, wildlife, and
economic values.
182
With the exception of SO
2
, for which the secondary standard is margin-
ally stricter than the primary one,
183
the primary and secondary NAAQS for
each criteria pollutant have always been set at the same level. EPA devotes
the bulk of its regulatory energy to developing primary standards that can
shield against the human health consequences of air pollution, and then sim-
ply adopts the primary standard to serve as a secondary one.
184
In the case of NO
2
, EPA has done this in spite of growing evidence that
the primary standard is insufficient to protect ecosystems and species, in-
cluding ESA-listed species and their habitats.
185
This is precisely the kind of
situation that section 7 consultation is positioned to arbitrate and address,
especially since EPA has not only discretion, but also a mandate to set
NAAQS at levels that protect soils and wildlife. The need for and the value
of section 7 consultation in the setting of NAAQS for NO
2
becomes even
more apparent when we consider that EPA has, in the past, declined to revise
NAAQS for NO
2
. Until a few months ago, the standard remained effectively
unchanged since its initial promulgation in 1971.
186
EPA considered it ade-
quate to “protect vegetation and materials from the direct effects of NO
2
.”
187
179
42 U.S.C. § 7409(d) (2006); see also R
EITZE
, supra note 158, at 42.
R
180
42 U.S.C. § 7409(b)(1) (2006).
181
42 U.S.C. § 7409(b)(2) (2006).
182
42 U.S.C. § 7602(h) (2006).
183
See R
EITZE
, supra note 158, at 38.
R
184
See id. at 3738.
185
Fenn et al., Ecological Effects, supra note 7, at 41116.
R
186
See R
EITZE
,supra note 158, at 42; Primary National Ambient Air Quality Standards
R
for Nitrogen Dioxide, 75 Fed. Reg. 6474 (Feb. 9, 2010) (to be codified at 40 C.F.R. pts. 50,
58). On February 9, 2010, EPA introduced a stricter NAAQS for NO
2
. The new NAAQS adds
a short-term, one-hour daily maximum for ambient NO
2
concentrations to the existing annual
average of allowable NO
2
concentrations. See id. There is, as yet, no data on the extent of
compliance with this new standard. In other words, we do not yet have the data to determine
(1) whether the relevant California air quality districts (i.e., districts within the airshed of
relevance to the checkerspot) are in compliance with the new standard, or (2) whether the new
standard will enable any appreciable extra protection to California serpentine grasslands and
their checkerspot inhabitants.
187
R
EITZE
, supra note 158, at 42. Not only was EPA not considering anything beyond
R
direct effects, but also past reviews of NAAQS for NO
2
were only conducted because NGOs
sued to compel the agency to comply with the periodic NAAQS review required under the
CAA. See id.
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470 Harvard Environmental Law Review [Vol. 35
EPA regulatory decisions on the setting of NAAQS for NO
x
, including
any EPA decision to set the secondary standard at the same level as the
primary one, are therefore obvious candidates for section 7 jeopardy and
critical habitat consultation. Furthermore, to the extent that EPA practice has
effectively mooted secondary NAAQS by making them the same as the pri-
mary ones,
188
it may be most appropriate for EPA to consult the FWS when it
conducts the required 5-year review and revision of the primary NAAQS for
NO
x
.
Regardless of how the demarcation between primary and secondary
NAAQS is handled in the future, the nationwide uniformity of NAAQS will
make section 7 consultation over the setting of these standards a fairly com-
plex, or at least labor- and data-intensive process. The consultation will
have to consider the impact of a proposed NO
2
NAAQS on all listed species
and their designated critical habitat. This will require knowledge of the sen-
sitivity of listed species and their habitat to additional nitrogen deposition,
including but not limited to the calculation of critical loads for nitrogen for
the ecosystems where listed plant and wildlife species are found. Once such
data is considered, EPA might end up having to set the primary or secondary
NAAQS for NO
2
low enough to protect the most nitrogen-sensitive listed
species and critical habitats. This is obviously a non-trivial task.
E. SIPs and the Control of Nitrogen Impacts on Listed Species
In this situation, EPA consultation over the permitting of individual
emitters is insufficient to address the full extent of emission impacts on the
more nitrogen-sensitive listed species.
189
Consultation over the setting of
NAAQS for NO
2
, while technically well-positioned to accomplish improved
protection of listed species and their critical habitats, also presents some sig-
nificant practical challenges.
In this context, the design and implementation of SIPs stands out as a
potentially more practical way to ensure that air quality in general, and NO
x
emissions in particular, do not jeopardize listed species or damage their hab-
itats. This is because the CAA rules for SIP design give states significant
flexibility in deciding on the specifics of emissions control regulations.
190
These specifics include the exact conditions stipulated in emissions permits,
the use and nature of transportation planning and transportation control mea-
sures, and the distribution of regulatory burdens among different types of
188
Id. at 16, 3738; Ayers & Kornreich, supra note 177, at 17.
R
189
Many individual permits are administered by state air quality agencies, but EPA still
considers CAA permitting of new sources permitting which it has largely delegated to the
states to be a federal action for the purposes of ESA section 7 consultation. See, e.g.,
Bogert, supra note 147, at 583 n.212.
R
190
As long as a SIP can ensure the attainment of the relevant NAAQS, the state agencies
designing and implementing the SIP have considerable discretion as to the nature, mix, and
specifics of the planning and regulatory measures that go into such a plan. See 42 U.S.C.
§ 7410 (2006).
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sources and different emitters.
191
SIP planning thereby presents good oppor-
tunities for tailoring emissions controls to the specifics of regional air quality
needs, including the need to give nitrogen-sensitive species and their critical
habitats greater protection from emissions of adjacent and upwind sources.
However, EPA itself has very little control over the content of SIPs or
the SIP planning process. EPA does, on the other hand, have the authority to
approve or deny state SIPs.
192
Given the now known potential of nitrogen
emissions to jeopardize listed species and their critical habitat, it would be
logical for EPA to consult with the FWS prior to deciding whether to ap-
prove or deny a SIP dealing with the control and regulation of NOx. It
would also seem that where nitrogen-sensitive threatened and or endangered
species are present in a SIP planning area, EPA and the FWS should use
section 7 consultation to pressure state air quality agencies, such as CARB
and the BAAQMD, to include in their SIPs the kinds of regionally tailored
measures that can improve the protection of species against nitrogen-driven
jeopardy or critical habitat modification.
A recent Supreme Court decision, however, effectively takes away
EPA’s ability to consult with the FWS regarding SIP approval. In National
Association of Home Builders v. Defenders of Wildlife,
193
the Supreme Court
ruled that ESA section 7 requirements apply only to discretionary agency
actions. When an agency is required to act by statute, the Court reasoned, it
lacks the power to “insure that such an action will not jeopardize listed spe-
cies,” and should therefore not be expected to do so.
194
The Court’s analysis
in Home Builders leaves little doubt that EPA approval of a state SIP that
meets all the CAA SIP requirements is precisely the kind of non-discretion-
ary agency action that the Court considers exempt from section 7 require-
ments.
195
In sum, compared to the ratcheting up of NAAQS for NO
2
, strict
but regionally tailored emission controls imposed through SIPs may be a
more practical way of protecting the most nitrogen-sensitive among listed
habitats and species. Yet after Home Builders, EPA is legally precluded
from leveraging its SIP approval authority to push for such controls. Section
7 has the clear statutory and regulatory potential to help address the growing
species, habitat, and ecosystem threats of nitrogen deposition and to do so by
leveraging key provisions of the ESA against federal regulatory activities
taking place under the CAA. However, the practical difficulties with
NAAQS and the legal difficulties with SIP approval show that important
aspects of translating regulatory leverage into actual regulatory and manage-
ment practice still need to be worked out.
This situation perhaps helps to further underscore the importance of
having some recourse to section 9 in the search for solutions to the problems
191
See Reitze, supra note 134, at 21214; Dwyer, supra note 134, at 11981200.
R
192
42 U.S.C. § 7410(k) (2006).
193
551 U.S. 644 (2007).
194
Id. at 647. See Bogert, supra note 147, at 56768.
R
195
None of the CAA SIP requirements deals with the impact of SIP planning on ESA-
listed species. 42 U.S.C. § 7410a(2)(A)(M) (2006).
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472 Harvard Environmental Law Review [Vol. 35
that nitrogen deposition poses for the checkerspot and other nitrogen sensi-
tive species and ecosystems. Since the section 9 take prohibition applies to
federal and state agencies alike, it is perhaps somewhere within section 9
that the incentives can be found which will prompt or force state air quality
and emissions control agencies to tailor their SIPs and other state-level
air quality regulations in ways that are responsive to the different species
and ecosystem tolerances towards nitrogen deposition. In other words, sec-
tion 9 might provide incentives for states to act in ways that help mitigate
the threats of nitrogen deposition to listed species while also helping avoid
the potentially cumbersome regulatory task of tailoring all air quality stan-
dards to the sensitivity thresholds of the most sensitive habitats and species
(a situation that, as discussed above, may occur if section 7 leverage is ap-
plied to EPA’s setting NAAQS).
Alternatively, caught between the “incisors” of section 9
196
and the in-
creasingly clear yet potentially difficult to follow requirements of section 7
(requirements with regard to NAAQS), EPA might be motivated to seek new
ways of collaborating with the states to arrive at methods of controlling ni-
trogen emissions and ambient levels that are regionally tailored, practically
sensible, and simultaneously compliant with the relevant mandates of the
ESA and the CAA.
VI. T
HE
P
ROS AND
C
ONS OF
L
EVERAGING THE
ESA
AS A
T
OOL FOR
R
EDUCING
E
COLOGICALLY
H
ARMFUL
N
ITROGEN
E
MISSIONS
To determine the wisdom of leveraging the ESA to attain reductions in
harmful nitrogen emissions, it is ultimately important to consider not only
the more technical side of the statute’s regulatory versatility, but also the
likely political and practical consequences of such strategic leveraging.
In doing so, we begin once again by drawing a comparison between the
nitrogen emissions and the GHG emissions cases. In spite of the clear and
momentous impacts of climate change on imperiled species, prominent ESA
scholars have advanced some important objections against using the ESA to
regulate GHG emissions.
197
Such objections are prompted by concern that
using the ESA as a control on GHGs will not only be legally and practically
difficult, but also ultimately ineffective in shielding listed species against
climate change. Further, regardless of the ultimate legal and ecological suc-
cess of such endeavors, attempting to leverage the ESA in this way is ex-
pected to produce more backlash against the statute, while also directing
196
See Paul Boudreaux, Understanding “Take” in the Endangered Species Act, 34 A
RIZ
.
S
T
. L.J. 733, 733 (2002) (“If the federal Endangered Species Act . . . is the pit bull of the
environmental statutes because of the power of its commands, then the Act’s take prohibition
would seem to be the dog’s incisors.”).
197
See, e.g., Ruhl, Endangered Species Act, supra note 14, at 275, 27980, 289; Baur,
R
supra note 14.
R
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2011] Tzankova et al., Nitrogen Deposition 473
scarce agency resources away from areas where aggressive ESA implemen-
tation would likely produce the greatest species and conservation benefits.
198
Notably, J.B. Ruhl concludes his extensive analysis of the ESA’s limits
in protecting imperiled species from the impacts of climate change by
stating:
Going for the jugular by regulating greenhouse gas emissions is
not where the ESA can be of most help to imperiled species.
There is little to be gained for the FWS or for climate threatened
species by having the agency go down this road. The agency has
no explicit authority to do so, does not have the expertise to do so,
and would risk undermining the political viability of the ESA by
doing so. Rather, the FWS can provide expert assistance to the
agencies more appropriately charged with regulating GHG emis-
sions, such as the EPA, by advising them about the effects of cli-
mate change on species.
199
At the same time, the analysis we have offered suggests that nitrogen
emissions and nitrogen deposition present a case that is sufficiently different
from that of GHG emissions and climate change a case where extending
ESA provisions to address the habitat and species impacts of nitrogen emis-
sions has the promise to be both much less legally difficult and much more
effective from a conservation standpoint than a similar extension in the GHG
case.
This is partly because the task of proving causation, while by far not
trivial, is more easily surmountable in the context of nitrogen emissions,
nitrogen deposition, and checkerspot injuries than it is in the context of GHG
emissions, climate change, and polar bear harm. In both cases, there is a
daunting causal challenge to link the impacts of macro-scale phenomena all
the way back to the individual, micro-scale acts of emissions ultimately (if
cumulatively) responsible for such macro-scale phenomena.
200
In the nitro-
gen case, this challenge is largely obviated by the aggregation of emissions
responsibility within a small number of federal and state regulatory agencies.
These agencies are responsible for controlling and permitting nitrogen emis-
sions through a combination of ambient and technological standards, re-
gional planning, and individual permitting. The existence of a separate and
well-established regulatory framework for the control of air quality and ni-
trogen emissions, and the flexibility agencies have for their regulatory ac-
198
See Ruhl, Climate Change, supra note 13, at 5862; Ruhl, Endangered Species Act,
R
supra note 14, at 275, 27980, 289; Baur, supra note 14; see also John Kostyack & Dan Rohlf,
R
Conserving Endangered Species in an Era of Global Warming, 38 Envtl. L. Rep. (Envtl. Law
Inst.) 10,203, 10,212 (2008) (providing a set of detailed recommendations for implementation
by the ESA to address climate change effects).
199
Ruhl, Climate Change, supra note 13, at 59.
R
200
See Ruhl, Climate Change, supra note 13, at 4647, and Gerhart, supra note 15, at
R
18995, for a detailed discussion of the seriousness of these challenges in the context of cli-
mate change.
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474 Harvard Environmental Law Review [Vol. 35
tions under that framework are what ultimately allow for such aggregation of
responsibility. This framework and flexibility should enable a successful
leveraging of ESA provisions against harmful nitrogen emissions. Compa-
rable conditions are conspicuously absent in the GHG case.
Together with the physical dynamics of nitrogen transport and deposi-
tion,
201
this aggregation of responsibility for nitrogen emissions should also
make the ESA a lot more effective in attaining meaningful protections for
the checkerspot. Unlike in the GHG case, the vast majority of the offending
nitrogen emissions are fully within the jurisdiction and regulatory control of
a relatively small number of federal and state agencies, which are in a posi-
tion to regulate such emissions to better protect listed species that are partic-
ularly vulnerable. A nudge from the ESA toward stricter NAAQS, for
example, could provide these agencies with the impetus to do so. Using the
ESA to address the problem of nitrogen deposition will, to a significant ex-
tent, entail the leveraging of its section 7 and section 9 provisions against
existing air quality statutes, and against the federal and state agencies re-
sponsible for implementing these statutes.
This also means that leveraging the ESA to regulate the nitrogen emis-
sions responsible for harming listed species will not require the FWS to deal
with something it lacks the experience and expertise to address. That is,
leveraging the ESA to help the checkerspot and other listed species affected
by nitrogen deposition will not be putting the FWS (or NMFS) in the busi-
ness of regulating emissions and air quality. Rather, a successful ESA case
against nitrogen emissions will compel the FWS to work with EPA and state
air quality agencies to ensure that the ambient air quality standards and ni-
trogen emission regulations that such agencies are promulgating under al-
ready existing statutory mandates are developed with the protection of listed
species in mind. This is something which the FWS should have both the
authority and expertise to do.
What would a court finding nitrogen emissions as a prohibited take of
checkerspots produce in terms of changes and adjustments to current air
quality and emissions regulations or regulatory practices? And what can
section 7 consultations over NAAQS, emissions trading programs, or tech-
nology-based emission standards for NO
x
be expected to produce, in terms
of recommendations and protections in the FWS BOs? Many of the details
will have to be ironed out in the course of actual practice. Further, it is
possible that regardless of the practical, on-the-ground changes it manages
or fails to produce, a successful legal challenge against nitrogen emissions,
leveraging ESA against federal and state air quality and nitrogen emissions
regulations and regulators, would still bring about another round of perilous
anti-ESA backlash.
201
These dynamics entail relatively short residence time of biologically reactive nitrogen
in the atmosphere, as well as local and regional rather than global transport of such
reactive nitrogen prior to deposition.
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2011] Tzankova et al., Nitrogen Deposition 475
Yet, in considering whether it is worth acting to deploy the ESA’s regu-
latory potential towards addressing an increasingly important, if chronically
underemphasized threat to listed species (and ecosystems more broadly), we
side with Robert Irvin. Irvin looks at the much greater challenge (and
greater unknown) of using the ESA to address the GHG drivers of climate
change to conclude that “[t]o arbitrarily decide that the ESA should not be
used to consider the impacts of greenhouse gas pollution on polar bears or
other species imperiled by climate change is to ignore the law’s potential to
stimulate creative solutions to seemingly intractable problems.”
202
Ditto for
the increasingly significant and increasingly troubling impacts of nitrogen
pollution.
202
Irvin, supra note 15, at 10,751 (emphasis added).
R
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