ArticlePDF Available

Conflicts Associated with Dam Removal in Sweden

Authors:
anna.lejon@emg.umu.se
anna.lejon@emg.umu.se
anna.lejon@emg.umu.se

Abstract and Figures

The increasing number of deteriorating old dams that need renovation or have lost their function make dam removal a viable management option. There are at least four major reasons for dam removal: safety, law and policy, economy, and ecology. Here we discuss 17 Swedish dams that were recently considered for removal. Because dam removal usually causes controversy, dam removal initiatives may succeed, fail, or result in a compromise such as a bypass channel for migrating fish. We identify and discuss three major obstructions to dam removal: funding, cultural-historical values, and threatened species. To facilitate dam removal, the reasons for, and the effects of, dam removal must be carefully explained, and the public and stakeholders must be kept informed. In complicated cases in which compromise solutions may be the most feasible outcome, the integration of the knowledge of different stakeholders is crucial. The involvement of diverse stakeholders increases their willingness to find compromises, thus avoiding conflicts and failures.
Content may be subject to copyright.
Copyright © 2009 by the author(s). Published here under license by the Resilience Alliance.
Lejon, A. G. C., B. Malm Renöfält, and C. Nilsson. 2009. Conflicts associated with dam removal in
Sweden. Ecology and Society 14(2): 4. [online] URL: http://www.ecologyandsociety.org/vol14/iss2/art4/
Insight
Conflicts Associated with Dam Removal in Sweden
Anna G. C. Lejon 1, Birgitta Malm Renöfält 1, and Christer Nilsson 1
ABSTRACT. The increasing number of deteriorating old dams that need renovation or have lost their
function make dam removal a viable management option. There are at least four major reasons for dam
removal: safety, law and policy, economy, and ecology. Here we discuss 17 Swedish dams that were
recently considered for removal. Because dam removal usually causes controversy, dam removal initiatives
may succeed, fail, or result in a compromise such as a bypass channel for migrating fish. We identify and
discuss three major obstructions to dam removal: funding, cultural-historical values, and threatened species.
To facilitate dam removal, the reasons for, and the effects of, dam removal must be carefully explained,
and the public and stakeholders must be kept informed. In complicated cases in which compromise solutions
may be the most feasible outcome, the integration of the knowledge of different stakeholders is crucial.
The involvement of diverse stakeholders increases their willingness to find compromises, thus avoiding
conflicts and failures.
Key Words: controversies; dam removal; information; obstructions; reservoirs; rivers; stakeholder
involvement; Sweden
INTRODUCTION
During the 20th century, humans dammed and
regulated most of the world’s rivers for reasons such
as hydropower, flood control, domestic water
supply, and navigation (Nilsson et al. 2005).
Globally, there are now about 50,000 dams
exceeding 15 m in height (WCD 2000), and many
new dams are planned or under construction (WWF
2004). There is no current record of the global
number of small dams, i.e., dams <15 m in height,
but in the United States alone there are
approximately 2 million such dams (Shuman 1995).
Among Sweden’s more than 5300 dams, about 5100
(96%) are small (SMHI 1994, 1995, Vattenportalen
2007). Although human control over freshwater
flow has increased prosperity for many people, it
has also led to serious effects on ecosystems and
local human societies (e.g., Nilsson and Berggren
2000, Scudder 2005).
Dams increase water retention, modify the
hydrograph, eliminate turbulent reaches and
riparian wetlands, impede the dispersal and
migration of plants and animals, decrease
interactions between land and water, and reduce
sediment transport (Ward and Stanford 1995,
Jansson et al. 2000, Kingsford 2000, Syvitski et al.
2005). Following the creation of dams and
reservoirs, many terrestrial ecosystems become
permanently inundated. This damages ecological
communities, erodes the soil of the inundated land
(Dudgeon 1995, Nilsson et al. 1997), and causes
emissions of greenhouse gases such as methane and
carbon dioxide during the breakdown of organic
matter (Fearnside 1997, St. Louis et al. 2000). Even
if not directly affected by loss of property, humans
are often indirectly affected by hampered ecosystem
services such as reduced water availability on
farmed floodplains following decreased flooding,
lowered aquatic productivity, and reduced control
of species invasions (Nilsson et al. 2005).
During the Swedish dam-building era after World
War II, large, modern hydroelectric power plants
were constructed to supply the developing industry
and society with electric power. In some cases, small
dams, such as hydroelectric dams and splash dams
used for timber floating, were removed to make
room for larger ones. In this respect, dam removal
is not a new concept in Sweden. However, the
removal of entire impoundments and dam
1Umeå University
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
constructions to restore riverine landscapes is a new
practice. Thus, dam removal is becoming a more
frequently used management option, especially for
old dams in need of renovation and small dams that
are no longer used or have lost most of their reservoir
capacity. Globally, most dams that have been
removed or considered for removal are in the USA.
In 2003, Stanley and Doyle (2003) reported that
more than 500 dams had been removed in the
previous two decades in the United States, although
they found no data indicating that any other country
had removed more than nine.
Dam removal is now becoming a viable option in
other regions of the world for several reasons. For
the dam owner, removal can be economically
preferable to renovation because of the
environmental benefits gained from the restoration
of turbulent stream reaches and fish migration
routes. Safety reasons are also vital, especially in
cases in which dams are in bad shape and hold large
amounts of water (Stanley and Doyle 2003). Despite
such benefits, however, dam removal often gives
rise to conflicts. This is the case even when dam
owners encourage removal. Conflicts often result in
unnecessarily long processing times, and
sometimes removals are stalled even in cases in
which funding for removal has been provided. In
this paper we address incentives for dam removal
such as safety issues, law and policies, and
economic as well as ecological incentives. We also
outline some of the underlying mechanisms of the
types of conflict associated with dam removal. Our
presentation is based on our own experience with
recently debated and implemented dam removals in
Sweden (Table 1). We also provide guidance on
how conflicts can be prevented or resolved in future
dam removals.
INCENTIVES FOR DAM REMOVAL
Early dam removals were often motivated by safety
considerations but, during the 1990s, environmental
motives became more prevalent. In some cases,
removal offers direct economic advantages. We
here discuss four drivers of dam removal: (1) safety,
(2) law and policy, (3) economics, and (4) ecology.
Safety
All dams have limited life spans, and dams that are
not maintained eventually fail (David and Baish
2002, Palmer et al. 2008). Numerous dams around
the world are in need of inspection, because dams
at risk of failure as a result of future climate changes
and possible severe floods may pose serious threats
to humans and infrastructure. Climate change is
predicted to alter global water cycling, and, within
40 yr, some of the largest rivers may have doubled
the amount of water they discharge. Impounded
rivers are not designed for discharge outside their
range of variability, which makes them less capable
of managing these alterations compared to free-
flowing rivers (Palmer et al. 2008).
Dams may also fail because of reservoir
sedimentation (Evans et al. 2000). The
sedimentation rate is highest during floods and
violent storms, and even mudslides caused by
earthquakes can have unpredictable effects on
reservoir sedimentation. Changing climates may
cause more intense storms that will probably
increase the rate and unpredictability of
sedimentation (Emanuel 2005, Webster et al. 2005).
For example, one of the worst dam collapses in
history occurred in Henan province, China, in
August 1975. The Banqiao dam was built on the
Huai River, a tributary of the lower Yangtze, and
was considered to be an indestructible dam that
could never fail. When a typhoon and a cold front
collided over Henan province, the Banqiao reservoir
filled to close to maximum capacity in a single day.
Even though its sluice gates were open, they became
partly blocked by sediment, which caused the water
level of the reservoir to rise to more than 2 m above
its designed capacity in 24 h. The dam collapsed the
next day, and 500 Mm³ of water rushed downstream
at a speed of 50 km/h, drowning entire villages and
towns. This precipitated the failure of as many as
62 dams, causing the deaths of 230,000 people
(McCully 2001).
In a more recent example from May 2008, a major
earthquake struck eastern Sichuan, China, with a
magnitude of 7.9 on the Richter scale. More than
69,000 people were killed, and the earthquake was
felt in most of central, eastern, and southern China
(U.S. Geological Survey 2008). In the southern parts
of the Quangxi region, rain and floods after the
earthquake exerted tremendous pressure on six
dams that were in danger of bursting, and people
were evacuated downstream from one of the dams,
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Table 1. A list of Swedish dams and rivers subjected to/considered for restoration and the issues involved
in the process.
Name River Height
(m) Built Removed Original use Reason for removal/
compromise
Gate
kvarndamm Gatebäcken 3 1880 Not
removed Water mill Facilitate fish passage
Issues: The dam owners wanted to keep their lake and were not in favor of a removal without compensation. Financial
difficulties because of expensive consultants led to a compromise in the form of a fish passage. This later came to nothing,
and the dam was left intact.
Forsby power
station Testeboån 4.8 1927 2005 Electricity (400 kW) Facilitate fish passage
Issues: The power company and local politicians opposed removal and argued that removal would trigger a chain reaction
leading to dam removals all over Sweden. Some years later, the power station was no longer profitable, and extensive dam
renovations were required. A removal was agreed upon. Adjacent neighbors opposed removal to the very end mainly
because they feared a dried-up ditch would result.
Unnefors
dam Nissan 2.3 1924 2007 Sawmill/
electricity Facilitate fish passage
Issues: Adjacent neighbors wanted to keep the impoundment for recreational purposes. The dam owner, a sawmill
company, was opposed to removal at first but changed its mind when a second alternative was presented. They had one
condition: that the natural channel be redug further to the northeast to provide the mill with an extended timber yard in the
former impoundment.
Kuba dam Nätraån 3 1974 2007 Storage reservoir for process
water used in factories Abandoned dam, facilitate
fish passage and reproduction
of freshwater pearl mussel
(Margaritifera margaritifera)
Issues: The local fishing organization had been advocating the removal of this dam for many years but was not able to
raise the money needed. The county administration eventually wrote a petition, and funding and permission were granted.
Bultfallet Kolbäcksån 4.2 1923 Replaced Electricity (800 kW) Abandoned dam
Issues: The power company got permission to remove the dam, which was abandoned and decaying, but the municipal
council was concerned with cultural-historical values. The cultural committee strongly opposed a removal, and local
inhabitants were afraid that the scenery would change dramatically after a removal. The old dam was eventually removed
and replaced with a new one.
Bruksfallet Kolbäcksån 4.3 1906 Replaced Electricity (900 kW) Abandoned dam
Issues: Same as above.
(con'd)
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Rödå dam Rödån 4.5 1940 Not
removed Water mill/
electricity Increase biodiversity,
facilitate fish passage
Issues: The dam owner strongly opposes a removal and continues to put up resistance.
Åman lower
dam Åman 5 1940 Not
removed Electricity Electricity production too
profitable
Issues: Removal is probably not possible because of high electricity production. The construction of a fish passage is under
discussion.
Åman upper
dam Åman 6.5 1940 Not
removed Electricity Electricity production too
profitable
Issues: Same as above.
Emsfors dam Emån 3.5 Not
known Not
removed Electricity Facilitate fish passage,
increase biodiversity
Issues: The former dam owner refused to agree to necessary environmental measures. The new dam owner agreed to a
removal, but an adjacent property owner is now impeding the process by trying to get compensation. There are also
concerns regarding the wels catfish (Silurus glanis) population, which is one of the few remaining in Sweden; a complete
removal would have to include extensive work to maintain a suitable catfish habitat.
Franshammars
dam
Harmångersån
Not
known 1918 2002 Water mill/
electricity Facilitate fish passage
Issues: Adjacent neighbors were concerned about low water levels upstream if the dam were removed. Hälsingland
Museum claimed that the dam had historical value and should have been left intact.
Sörtjärns dam
Harmångersån
Not
known Not
known 2002 Water mill Facilitate fish passage
Issues: Same as above.
Hisjö dam Visboån/
Flysån 3 Not
known 2007 Electricity Increase biodiversity
Issues: There were no obstacles.
Hillman’s
mill Norralaån 2.8 1912 Not
removed Water mill/
electricity Facilitate fish passage
Issues: In 2006, a fish passage was built so that the dam could be conserved for tourism.
Sunnäs
factory Tvärån 4 1696 Not
removed Forge/
sawmill Increase biodiversity
Issues: The forge and the adjacent mansion are both classified as cultural heritage sites, so dam removal was not an option.
The fish passage that was built in 2005 blends in esthetically with its surroundings. There was no opposition because of
good communication, and a solution was found that appealed to everyone involved.
(con'd)
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Kvarn dam
Söderhamnsån
1.5 1751 Not
removed Water mill Facilitate fish passage
Issues: The cultural committee and the environmental departments at the municipal office and the county administration
worked closely together so that upcoming problems could be solved without opposition or conflicts.
Långbo dam Skärjån 2 1918 Not
removed Water mill/
sawmill/
electricity
Facilitate fish passage,
increase biodiversity
Issues: The removal of this dam is still under discussion, and an optimal solution is hard to find. The dam is located very
close to the main road. Even though it is in bad condition, the village association would like to keep it. Any future fish
passage must be designed to take the location into account.
which had a reservoir capacity of 1.8 Mm³ of water
(Ruwitch 2008).
These facts make it necessary, at some point in time,
to assess a dam’s future, no matter what the reasons
were for building it and irrespective of whether it is
being used or not. In the case of nonfunctioning or
unused dams and reservoirs, there are good grounds
for removing them completely to avoid the hazards
caused by dam failures. The most common cause of
dam and reservoir aging is sediment filling. For
example, in a review of reservoirs in Romania,
Rãdoane and Rãdoane (2005) found that some of
them were half filled with sediment within 50 yr. In
the most extreme cases, artificial reservoirs can
completely fill with sediment within 10–20 yr
(Einsele and Hinderer 1997, Kelly 1997). A dam
with a sediment-filled reservoir no longer fulfils its
original purpose and, if it collapses, could cause
devastating turbidity and sediment deposition in
reaches further downstream. In reservoirs with low
sedimentation rates, constraints on dam construction
become critical for their life-span.
Law and policy
Water issues are now receiving a high priority on
the political agenda because of increasing
knowledge about the negative consequences of
human water usage. In many countries, dam
removals are supported by national policy and
legislation related to the protection and
enhancement of biodiversity in freshwater
ecosystems. For example, in Sweden, the
Environmental Objectives state 16 ecosystem goals
that should be reached by the year 2020 (Swedish
Government 2008). The objective that has the most
relevance for freshwater ecosystems concerns the
responsibility of maintaining flourishing lakes and
streams, good-quality groundwater, thriving
wetlands, and a rich diversity of plant and animal
life (Swedish Government 2008). One subgoal to
be accomplished while achieving this overall
objective is that 25% of valuable and potentially
valuable rivers and streams must be restored by
2010.
Strong regional laws and policy instruments may
also be an imperative for dam removal. By signing
the European Union Water Framework Directive,
member states have agreed to manage all water in
an ecologically sustainable way and to maintain its
ecological status (European Commission 2000).
Furthermore, the European Union Natura 2000
network and the Habitat Directive oblige the
member states to ensure the restoration or
maintenance of natural habitats (European
Commission 1992). Within these directives lie both
the opportunity and the obligation to restore waters
that have been degraded, such as those impacted by
dams. In comparison, in the USA two separate acts,
the Federal Power Act (FPA) and the Endangered
Species Act (ESA), play vital roles in the licensing
and relicensing of hydroelectric power dams
through the Federal Energy Regulatory Commission
(FERC). The ESA was formed to protect species
and the ecosystems in which they exist, whereas the
FPA regulates the development of power. Today, in
U.S. relicensing processes, dam operators must
consider the impact of their operations on the
riverine environment and the possibility of taking
preventive measures to mitigate negative impacts.
The ESA thus has a compelling effect on the
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
relicensing permissions handled by FERC (Blumm
and Nadol 2001).
Economic incentives
Under some circumstances it may be economically
more beneficial to remove a dam than to keep it,
even if it still produces revenue. For example, a
study of 14 dam removals in Wisconsin, USA,
showed that the estimated cost of repair was on
average three times higher than that of removal
(Born et al. 1998). One common consequence of
damming rivers is an impoverished fish fauna. Fish
production is often an important source of income
for local inhabitants, both directly as fish harvest
and indirectly as a resource base for tourism and
recreational fishing. The loss of income caused by
the loss of fishing can be greater than the value of
the power produced (Kruse and Scholz 2006). The
restoration of fishing can therefore be a strong
incentive for removing dams.
A recent survey among anglers who had visited the
Storsjö fisheries conservation area in central
Sweden revealed that the dam at Storsjö-Kapell
influenced the value that the anglers placed on the
catch (Laitila et al. 2006). If the dam were removed,
the economic value of a large fish would double and
the value of a fishing-day would increase by an
average of 537 Swedish kronor (SEK), even with
no change in the fish stock. It has been estimated
that a dam removal would make it possible to
quadruple fish stocks, which would increase the
value of a fishing-day by 1830 SEK. Such a scenario
would increase the number of fishing-days per
season by 72%, from 2000 to 3440 (Laitila et al.
2006).
In the United States, considerable resources are
spent every year on preserving threatened fish
species in regulated rivers (Revenue Stream 2008).
In the Columbia River Basin, the transportation of
juvenile chinook salmon by trucks from the
uppermost dams to the lowest dam has considerably
slowed the rate of decline of that species. Without
that specific aid, the salmon would probably have
disappeared from the Snake River. The removal of
the lower Snake River dams might increase the
physiological vigor of the salmon that swim
downstream and improve their survival (Kareiva et
al. 2000). Dam removal would end the need for out-
of-river fish transportation, which probably has
added to the annual costs of maintaining the dams
(Revenue Stream 2008). Dam removal is now
increasingly seen as a viable alternative to
maintenance, and even larger dams are being
considered for removal, the two dams on the Elwha
River providing one of the best examples.
The Elwha and Glines Canyon dams on the Elwha
River in Washington State, USA, were built in 1913
and 1927, respectively, and are scheduled for
removal in 2012. The upper portion of the Elwha
river basin is located within Olympic National Park,
and the lower reach at the river’s mouth is in the
Klallam Indian reservation. This tribe was the first
to demand dam removal, and its members pointed
out that the river formed an integral part of their
spiritual heritage and that the dam construction was
a tremendous injustice. For the tribe, dam removal
is of great importance because of deeply held
cultural and personal beliefs. Because the tribe also
relies economically on salmon fishing, restored fish
production would be of great financial value. The
two dams were built without fish ladders, although
state law at that time required them, and they
therefore disrupt salmon migration and block off
approximately 90% of their spawning habitat
(Gowan et al. 2006, Duda et al. 2008, Pess et al.
2008). Another case in which the removal of a dam
would provide economic benefits is that of
Sweden’s indigenous Sami people, especially those
who herd reindeer, an activity that has been
profoundly affected by dams and reservoirs in
northern Sweden. For example, the availability and
quality of reindeer pasture lands have decreased
because of the inundation of river valleys, and the
passage of rivers during migration periods has
become difficult because of modified flow and ice
conditions. Some compensation has been given to
the Sami people for damage and intrusion, but these
funds are not considered adequate compensation for
the difficulties caused (Morin 2006).
Ecological incentives
Dams alter many natural characteristics of and
processes in rivers. For example, by fragmenting
channels and modifying flows, they affect the
productivity of wetlands, floodplains, and deltas;
disrupt the migration and dispersal of riparian and
aquatic organisms as well as sediment dynamics;
and cause freshwater species numbers to decline
(Hart and Poff 2002, WWF 2004). Many dams with
large reservoirs, especially those that have
hypolimnetic release of water, also modify the
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
temperature regime of downstream reaches and lead
to shifts in biota (e.g., Gregory et al. 2002). In
general, impounded rivers are considered to favor
the invasion of non-native species, thus exerting
further pressures on the biota (Stanford et al. 1996,
Johnson et al. 2008).
Although dams and reservoirs have many ecological
effects, the disruption of the movement of different
organisms is probably the most important reason for
removing dams. Dam removal makes it possible for
fish passage and fish taxa to shift from lentic to lotic
species, which have the potential to migrate and
reproduce along free-flowing watercourses (Hart et
al. 2002, Stanley and Doyle 2003). The St. Etienne
de Vigan dam on the Upper Allier River, a tributary
of the Loire River in France, may serve as an
example. This dam was removed in 1998 to provide
access to salmon spawning grounds. The removal
was part of the French government’s program to
restore the salmon population in the Loire basin, and
the aim was to have 6000 salmon return to the
estuary in 2008 and to ensure the environmental
protection of the Loire River. The river has returned
to a near natural state, and, in the winter of 1998–
1999, five salmon spawning sites were found
upstream of the former dam (RiverNet 2008).
As mentioned, dam removal is beneficial to
migrating fish, and eel is a species that has suffered
a severe reduction in stock numbers because of dam
constructions. European eel (Anguilla anguilla)
spend most of their lives in fresh water in northern
Europe. However, they breed in the Sargasso Sea,
so that free passage to the sea is crucial for spawning
(Laffaille et al. 2005, Acou et al. 2008). Also, the
migration route of eels has changed because of dam
constructions that add significantly to the
difficulties of spawning (Degerman et al. 2001). Sea
trout (Salmo trutta) is another example of a fish
species impeded by dams, not only during its
upstream spawning journey but also on its way back
to the sea. Apart from newly spawned adults, smolts
experience a dangerous journey downstream trying
to pass dam constructions without getting killed in
the turbines (Coutant and Whitney 2000). Common
whitefish (Coregonus lavaretus) spawn in lakes,
streams, or the sea. During the summer months, the
species moves toward colder and deeper waters
(Swedish Board of Fisheries 2008), and free passage
is a prerequisite for its natural migration patterns.
Climate change may also be an important reason for
dam removal (cf. above). Although many rivers will
face increased discharge in the future, others may
experience a considerable flow reduction. With
increasing temperatures, reservoirs in warm and dry
areas will lose even more water through evaporation
in addition to the approximately 3.5 % that now
evaporates every year. The fact that reservoirs trap
large amounts of sediment reduces the nutrient
supply to the sea and causes coastal deltas to shrink
(Ericson et al. 2006, Palmer et al. 2008). Dam
removal could thus be a feasible means of adapting
to escalating climate change (Palmer et al. 2008).
Also, in the future we will need replacement water
supplies and far more effective and equitable
conservation measures if and when reservoir storage
is diminished because of dam removal.
Dam removal is also a feasible method of restoring
habitats, flow patterns, and migration paths. It is
possible to restore these three riverine components
more or less separately or in different combinations
depending on the results required. The initiative to
remove dams originated quietly in the USA as early
as 1931, when a dam on the Idaho River was
removed, but the movement has continued to grow,
and, with Secretary of the Interior Bruce Babbitt as
spokesman, the issue was brought into the U.S.
political arena (Klein 1999). As mentioned above,
in Sweden the practice of using dam removal as an
ecological restoration method is rather new.
DAM REMOVAL IN SWEDEN
In Table 1 and Fig. 1 we present a compilation of
the cases of 17 dams in different parts of Sweden
that have all been considered for removal. In six of
the 17 examples, the dams have been completely
removed, five to improve fish passage and one to
increase general biodiversity. The creation of fish
passage was one of the reasons for removal in 12 of
the 17 examples, and it was the only reason in seven
of those 12. Increased biodiversity was a reason for
removal in five of the 17 examples, and it was
claimed as the only reason in three of those five.
Small-scale electricity production was a main or
subordinate use for 11 of the 17 dams. These
examples provide a general idea of the work done
and of the issues and incentives entailed in the
removal and decision-making processes. Table 1
also points out that the work involved various kinds
of problems, including strong wills, contrasting
opinions, and, at times, misconceptions rooted early
on in the process. Three cases, all located within the
same municipality, constitute a specific situation
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
because, despite contrasting opinions, everyone
involved was willing to work for a consensus.
CONTROVERSIES ASSOCIATED WITH
DAM REMOVAL
Given the many negative consequences of dams for
ecosystems, one would assume that, if a dam owner
decided to remove an old, inefficient dam, people
would support that decision. However, this is often
not the case. Instead, dam removal operations are
often subjected to a number of different obstacles
that may postpone or stop the process. One might
wonder why dams are seen as monuments of human
engineering skills, or why they raise indignant
feelings in proponents as well as opponents of
removal. The U.S. politician and dam removal
proponent Bruce Babbitt said,
I always wonder what is it about the sound
of a sledgehammer on concrete that evokes
such a reaction? We routinely demolish
buildings that have served their purpose or
when there is a better use for the land. Why
not dams? For whatever reason, we view
dams as akin to the pyramids of Egypt—a
permanent part of the landscape, timeless
monuments to our civilization and technology.
Born et al. (1998) studied the process leading to the
removal of 14 dams in Wisconsin, USA, and found
that, in all cases, citizens originally opposed
removal when it was first discussed at stakeholder
meetings. The most vocal opponents in their study
were riparian landowners and the local communities
around the impoundments. In cases in which
riparian landowners represented a majority of
stakeholders, i.e., dams were located in the middle
of communities rather than more rural settings, the
dams ended up being repaired instead of removed,
despite a higher cost for the dam owner. Born et al.
(1998) also categorized the perceived gains and
losses following removal and found that
stakeholders in 12 of the 14 cases felt that improved
safety was a gain. Stakeholders also listed improved
fish and wildlife habitats as a reward.
Despite the fact that many Swedes are highly aware
of ecological matters and willing to pay for healthy
ecosystems (Sundberg and Söderqvist 2004),
ecological values must frequently take a back seat
when money and reluctance, which often originate
from fear of change and the unknown, come to play
vital roles in dam removal processes. Even strong
arguments for removal may not convince
opponents. People tend to have major misconceptions
about what will happen after a dam is removed, and
there is a common misunderstanding that the
removal of a dam will alter the scenery in a negative
manner, for instance, that there will be nothing left
but a pool of mud (Sarakinos and Johnson 2003).
For example, this was the main objection to the
removal of the Unnefors Dam (Table 1; B. Lind,
personal communication). Orr and Stanley (2006)
showed that vegetation established quickly
following dam removal and that less than 1% of all
sampled areas was bare sediment even on sites
restored as recently as a year previously. We also
saw the rapid recolonization of the soil of the former
reservoir after the Kuba dam was removed (Table
1, Fig. 2). Measurements of production capacity in
this former reservoir also showed that it was
significantly higher compared to reference sites,
probably because of nutrient-rich sediments and
good access to sunlight (Hörnström 2009). If people
are not familiar with the meaning of words such as
“change” and “restoration,” they easily give them
negative connotations. Therefore, neighboring
landowners and people living adjacent to a dam tend
to oppose the idea of dam removal.
Owners of dams and land play important roles in
the decision-making process, but, unfortunately,
their opinions are often based on inaccurate facts
(David and Baish 2002, Graf 2003). Public
education is needed to overcome these
misconceptions. We as humans have tried to
disassociate ourselves from natural cycles and
processes by altering the structure and dynamics of
ecosystems so as to satisfy our immediate needs and
desires. Today’s conflicts between different societal
“needs” involve an attempt to communicate that
humans belong to ecosystems worldwide. Decades
of successive disassociation from nature leave many
people perplexed when the integration of human
societies and ecosystems is called for (Bradshaw
and Bekoff 2001). There are numerous dam
removals in Sweden that have come to a halt
primarily because of reluctance (cf. above). People
wish to keep their lake for recreational purposes
rather than gaining free-flowing water. Another
common misunderstanding is that dam removal will
cause property values to drop (Sarakinos and
Johnson 2003, Provencher et al. 2008).
In 2006, we undertook a project to examine the
ecological effects of dam removal in Sweden. This
project followed a comparative design in which we
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Fig. 1. Locations of the Swedish streams and dams studied (see also Table 1).
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Fig. 2. Recolonization of vegetation on the soils of the former reservoir upstream of the Kuba dam
occurred within a few months after dam removal. (A) The former reservoir in May 2007, (B) the same
site in September 2007.
matched dammed sites with reference sites that had
not been affected by dams before and after dam
removal (cf. Stewart-Oaten et al. 1986). Because of
changes in plans at the municipal or county
administrative level, we experienced setbacks in our
fieldwork. For various reasons, dam removal plans
often change late in the approval process, and
several dams that had been close to removal
suddenly met with opposition. In a couple of cases,
we had actually begun pre-removal studies, and a
few months before a planned removal the process
unexpectedly came to a halt because of a sudden
lack of funds, stakeholder reluctance, or new
demands from landowners and neighbors. We
report on some of these obstacles and discuss their
causes. We have identified three generic
obstructions to dam removal:
1. Financing. Financial support to cover the
costs is often difficult to obtain because
usually funding from several sources is
required.
2. Cultural-historical values. These values are
often in conflict with the needs of the
ecosystem. Co-operation and a constructive
exchange of ideas would facilitate negotiations.
3. Threatened species. These species are subject
to intense protection programs. Even though
laws and regulations are in place to help
preserve viable populations of threatened and
endangered species in their natural habitats,
it can be difficult to balance what society
wants with the needs of the ecosystem.
The two cases (Gatebäcken and Kolbäcksån)
presented in more detail were chosen mainly
because they differ substantially from each other
and because they represent issues that need to be
addressed. Here reluctance also played a significant
role in the negotiations and decision-making
process. Experts, scientists, public authorities, and
others need to become better at pointing out and
communicating the various positive effects of dam
removal.
Funding obstacles
Funding is one of the major obstacles to dam
removal and one that makes it difficult to forecast
the outcome of removal plans. Usually, funding has
to come from different sources because expenses
are typically too high to be covered by a single
funder (Babbitt 2002). Whitelaw and Macmullan
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
(2002) present six analytical principles that should
guide the analysis of the economic consequences of
a decision to remove a dam. These deal with issues
related to benefits as well as costs, rights and
responsibilities, uncertainty, and sustainability. To
properly argue for removal and allocate funding, it
is thus important to have a clear picture of the
economic consequences of dam removal. There is
no guarantee that available funding will cover all
the costs involved in the process. Consulting firms,
contractors, landowners requesting compensation
for intrusion, and others all require their share of the
allocated funds.
For example, in 1880, a dam was built on
Gatebäcken in Hjo municipality, Sweden, to
provide a Norse mill with water, and in 1924 a
generator was installed to supply the mill with
electricity for lighting. This dam was due for
removal in 2007, when plans changed mainly
because of insufficient funding. The consulting firm
hired to write the proposal requesting the removal
permit turned out to be more expensive than
expected, and when the magnitude of the sediment
layers in the reservoir and the costs involved in
excavating them became clear, there was no other
option than to suspend the removal plans. The
municipality’s allocated funds were not sufficient
to compensate the dam owner as well as carry out
a complete removal. Instead, it was decided that a
fish passage should be built and that the
embankment and spillways should be strengthened
to keep the impoundment intact. A year later,
however, there were no funds left, and for the
moment no measures are being taken with regard to
this dam.
Another example is the removal of the Elwha and
Glines Canyon dams on the Elwha River. As part
of the deal, the federal government had to provide
a new water treatment plant, a new fish hatchery,
and other mitigation projects. These constructions
added significantly to the costs and time required to
remove the dam (National Park Service 2007,
Dunagan 2008, Gawley 2008). Because a large
portion of the watershed is within Olympic National
Park, which is managed by the National Park
Service, this constitutes an ideal setting for studying
the effectiveness of river restoration techniques,
thus perhaps paving the way for future large-scale
restorations. The U.S. government bills this project
as the largest decommissioning project in history,
and perhaps this fact, along with collaboration
among stakeholders and unique study opportunities,
keeps the project going even though the costs are
greatly inflated (Duda et al. 2008).
Cultural-historical obstacles
The cultural-historical values of dams and
associated constructions are other stumbling blocks
to dam removal, no matter how much those
structures are impinging upon the needs of the
ecosystem. In Sweden, as in other countries, there
are many old industrial communities, and the mills
and factories are often attractive old buildings with
preservation value. Dams used by the hydroelectric
power industry may have been in place for a long
time and have become accepted and valued parts of
the environment (e.g., Klein 1999). In such cases,
balancing the importance of functional ecosystems
and cultural-historical values is an arduous task.
When working to identify watercourses with high
conservation value, the Swedish EPA and several
county administration boards have cooperated with
the National Heritage Board to find common ground
in their judgments.
One example is the stream Kolbäcksån, which is
impounded by several dams and runs through the
old Swedish industrial community of Hallstahammar,
which has a metal industry as its core business. Two
of these dams, Bruksfallet and Bultfallet, are old
and in bad condition, so it would be desirable to
remove them. The dams were built in 1906 and
1920, respectively, to supply several factories with
electricity, but in 1989 a new and more efficient dam
fully replaced these and two other dams. The power
company that owns the dam was given court
permission for removal, but the municipal council
felt that it would be too large an intrusion into the
cultural-historical environment and the process
came to a halt. After examining these concerns, the
municipal council reached a unanimous decision
that the dams would not be removed but left intact.
As of today, an appeal has been lodged, and
negotiations have reached a deadlock. Fear of losing
recreational opportunities may be another factor
influencing this decision, because the communities
living close to the reservoir use it for swimming,
fishing, and boating. Some of the early opposition
to removing the Elwha dam came from people who
liked to go boating and fishing in the reservoirs (J.
Helfield, personal communication). Because a
reservoir often becomes central to a community’s
sense of place and is taken to be a natural part of the
environment, it can be difficult to persuade people
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
to change their minds. Klein (1999) elegantly
illustrates this point in her presentation of the pros
and cons of emptying Lake Powell on the Colorado
River.
The obstacle of threatened species and the risk
of spreading invasive species
Chapter 7, Section 11, of the Swedish
Environmental Code states that small land and water
areas that constitute habitats for endangered animal
and plant species or are otherwise particularly
worthy of protection may be designated habitat
protection areas, and that activities or measures that
are liable to damage the natural environment must
not be undertaken in habitat protection areas. Dams
and artificial impoundments give rise to “new”
habitats that some species may take advantage of.
For example, the stream Emån in southern Sweden
holds a population of Wels catfish (Silurus glanis
L.), which is an endangered species. The catfish is
considered to be a postglacial relict in this stream.
Bushes of grey willow (Salix cinerea L.) proliferate
in this impoundment, and the fish have been able to
use their tangled roots as breeding and hiding
habitats, thus surviving in the regulated stream.
Generally, catfish need slow-flowing streams with
natural river environments; water regulation is
therefore a threat to the fish and its natural
environment (Nathanson 1995).
Dams work as barriers that block the migration and
dispersal of invasive as well as native species.
Removal of a dam exposes a large area of reservoir
sediment that is highly conducive to plant
colonization, especially of invasive species.
Aggressive plant colonists may dominate for several
years if natives fail to survive because of strong
competition (D’Antonio and Meyerson 2002,
Shafroth et al. 2002, Orr and Stanley 2006).
Connectivity is often lost in aquatic ecosystems
because of dam construction. Consequently,
seasonal migrations of aquatic organisms are
prevented, and the diversity and productivity of
aquatic habitats are reduced. On the other hand, by
removing these barriers, river restoration may
increase the homogenization of aquatic biotas by
spreading non-native species. However, by
restoring former impoundments to free-flowing
stream reaches, fish composition will shift from
lentic to lotic, thus increasing biotic diversity and
allowing native species to return to their habitats
(Rahel 2007). Some faunal changes may occur
rapidly, whereas other long-term changes occur as
species adjust to changes in the channel (Hart et al.
2002).
Riverine organisms are always more or less affected
by dam removal before the state in the channel has
stabilized. Freshwater mussels are generally the
most negatively affected. Studies in Koshkonong
Creek, Wisconsin, USA, showed that 95% of the
mussels in the previously inundated area died
because of exposure and dehydration, and one
species disappeared entirely. Also, the mussels
downstream from the dam were affected by the
removal, and their density decreased from 3.8 to 2.6
mussels/m² in less than 3 yr because of increased
sedimentation (Sethi et al. 2004). The freshwater
pearl mussel (Margaritifera margaritifera L.) is a
red-listed and threatened species in Swedish
streams. This species lives its larval stage on the
gills of salmonid fish species, mainly brown trout
(Salmo trutta L.), and would likely benefit in the
long term from dam removal because this facilitates
trout migration. However, it is important to consider
the amount of sediment that could affect populations
located downstream. Elm (2004) concluded that,
despite the obvious benefits of removing the Örby
sawmill in Ljungån, Sweden, this could potentially
harm populations of freshwater pearl mussels in the
stream, because of both increased sedimentation
and the leakage of toxic waste from the former
sawmill, and cautioned against removal without a
thorough investigation of the harm it could
potentially cause.
RECOMMENDATIONS
Adequately applied, environmental legislation
should ensure that future generations will be able to
enjoy natural communities, free-flowing waters,
and thriving landscapes. One would imagine that
the removal of artificial objects from running waters
would generally be seen as a good thing, especially
in cases in which these objects no longer have any
socioeconomic value. However, in a surprisingly
large number of cases, this is not how dam removal
is perceived, and public perceptions of dam removal
and its consequences may seriously impede removal
projects. Although there are many reasons for this
resistance, they need to be understood to find
solutions that will benefit both nature and human
societies. Below, we present two basic tools that
could assist in this process.
First, reliable information about the effects of dams
and the effects of removing them is required. So far,
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Fig. 3. Unnefors Dam on the Nissan Stream before removal.
the idea of dam removal is unfamiliar to the general
public. Although dams are often seen as monuments
that should last (Babbitt 2005), it is reasonable to
ask whether it is realistic to preserve every old dam,
or whether there are ways to conserve the cultural
values of dams without making them into
untouchable monuments. As described above, there
was strong opposition to the removal of the
Bruksfallet and Bultfallet dams for cultural-
historical reasons, and these dams are to be
preserved unconditionally. However, there are dam
removals in which only pieces of the dam will be
preserved for historic purposes (David and Baish
2002), such as the Glen Canyon Dam on the Elwha
River. The obvious advantages of dams, such as
electricity generation and the creation of
recreational lakes, make it difficult to assess their
potential ecological damage, so that the eventual
benefits of dam removal may not be obvious.
Facilitation of fish migration and spawning is
generally an important reason for dam removal, and
it is also reasonably well understood. Game fish are
much easier to relate to than general ecosystem
qualities such as “increasing biodiversity.” Thus,
the careful formulation of the reasons for dam
removal and adequate education of the public are
important tasks that must be undertaken in each
case.
Second, stakeholder involvement is important. As
our results suggest, the involvement of a variety of
stakeholders increases their willingness to find
compromises, thus avoiding conflicts. An example
of this is the Unnefors Dam on Nissan stream (Figs.
3 and 4). In this case, the dam owner, a sawmill
company, agreed to co-finance the removal if they
were allowed to extend their timber yard. This
required a new channel stretch, and adjacent
neighbors were invited to influence its design. At
first, people opposed the removal, but education and
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Fig. 4. Nissan Stream after dam removal in July 2008. The channel is being redug (to the right in the
picture) so that the sawmill can expand its log yard out into the natural stretch. This was a demand from
the company in return for co-financing and agreeing to the removal. A and B mark the banks that will be
removed when the new channel becomes operational.
encouragement to get involved made them change
their minds. Especially in complicated cases in
which the goal is a compromise, the integration of
the knowledge of a diversity of stakeholders is
crucial for any outcome other than maintaining the
status quo. When those involved do not have a clear
understanding of what will happen when a dam is
removed, it can be hard to get different actors, such
as municipal offices, county administration boards,
research groups, and power companies, to cooperate
with each other. This may lead to overlapping work,
conflicts with stakeholders, and missed opportunities
to study the effects of dam removals. Again, in the
example of Bruksfallet and Bultfallet, the provision
of adequate information about safety issues related
to the deteriorating dams and the ecological benefits
of removing them could have avoided several
controversies.
More information should also be provided to
researchers. It is not uncommon for researchers to
be notified about a removal at such a late stage that
they have no time to carry out pre-removal studies,
which are fundamental for evaluating post-removal
recovery processes. In some cases, a removal may
be debated for years but carried out almost
immediately once the decision has been made, thus
limiting opportunities to conduct more extensive
studies. In contrast, researchers also run into
problems when they have begun pre-removal
studies and removal plans are cancelled or put on
hold for years. In the case of Gate kvarndamm on
Gatebäcken, time and money could have been saved
if the municipality had drawn up a financial plan
ahead of time. That way, unexpected and constantly
recurring expenses might have been avoided, giving
those involved a better opportunity to acquire and
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
allocate recourses and a better chance for a
successful removal. The fact that dam removal
studies can be joint ventures has to be taken into
consideration during research planning. Close
collaboration with all the bodies involved in dam
removal operations is the key to responsible use of
research resources.
When dealing with dam removals, the problems in
Sweden and the United States are similar. There are
no guidelines on how to approach dam removals
and troubleshoot problems, nor are there any long-
term studies to learn from, especially in the case of
Sweden, where dam removal still is in its infancy.
Hart et al. (2002) give an example of a risk
assessment framework for evaluating the potential
effects of dam removal. It is suggested that this
framework, under the right circumstances, can be
used to take into account many of the factors that
influence variations in potential responses to dam
removal. Even so, in both Sweden and the United
States, effective river restoration is only
accomplished when there is co-operation between
various protection and restoration practices. The
issues we have examined are unique because they
are Swedish examples and experiences, but also
because they are the first ones that have involved
researchers actively working with dam removals
and river restoration in Sweden. In fact, every dam
removal is unique, but the experiences gained are
applicable to almost any removal. Therefore,
sharing those experiences and making thorough
field and data analyses are of great importance
globally. Finally, whatever happens to dams in the
future, the dam removal movement will challenge
dam owners and operators to defend themselves,
and “to demonstrate by hard facts, not by sentiment
or myth, that the continued operation of a dam is in
the public interest, economically and environmentally”
(Klein 1999).
Responses to this article can be read online at:
http://www.ecologyandsociety.org/vol14/iss2/art4/responses/
Acknowledgments:
This research was supported by the Swedish Society
of Nature Conservation, the Swedish World Wide
Fund for Nature, and the Lamm Foundation. We
thank Rebecca Brown, James Helfield, and two
anonymous reviewers for constructive comments on
the manuscript.
LITERATURE CITED
Acou, A., P. Laffaille, A. Legault, and E.
Feunteum. 2008. Migration pattern of silver eel
(Anguilla anguilla) in an obstructed river system.
Ecology of Freshwater Fish 17:432-442.
Babbitt, B. 2002. What comes up, may come down.
BioScience 52:656-658.
Babbitt, B. 2005. Cities in the wilderness: a new
vision of land use in America. Island Press,
Washington, D.C., USA.
Blumm, M. C., and V. A. Nadol. 2001. The decline
of the hydropower czar and the rise of agency
pluralism in hydroelectric licensing. Columbia
Journal of Environmental Law 81:81-130.
Born, S. M., K. D. Genskow, T. L. Filbert, N.
Hernandez-Mora, M. L. Keefer, and K. A. White.
1998. Socioeconomic and institutional dimensions
of dam removals: the Wisconsin experience.
Environmental Management 22:359-370.
Bradshaw, G. A., and M. Bekoff. 2001. Ecology
and social responsibility: the re-embodiment of
science. Science and Society 16:460-465.
Coutant, C. C., and R. R. Whitney. 2000. Fish
behavior in relation to passage through hydropower
turbines: a review. Transactions of the American
Fisheries Society 129:351-380.
D’Antonio, C., and L. A. Meyerson. 2002. Exotic
plant species as problems and solutions in
ecological restoration: a synthesis. Restoration
Ecology 10:703-713.
David, S. D., and S. Baish, editors. 2002. Dam
removal: science and decision making. H. John
Heinz III Center on Science, Economics and the
Environment, Washington, D.C., USA.
Degerman, E., J. Hammar, P. Nyberg, and G.
Svärdson. 2001. Human impact on the fish
diversity in the four largest lakes of Sweden. Ambio
8: 522-528.
Duda, J., S. Brenkman, C. Orgersen, J. Dunham,
R. Hoffman, R. Peters, M. McHenry, and G.
Press. 2008. Impending removal of Elwha Dam
holds promise for salmon, researchers. People,
Land and Water. Available online at:
http://www.pe
oplelandandwater.gov/scienceandstewardship/
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
usgs_12-19-08_impending-removal-of.cfm.
Dudgeon, D. 1995. River regulation in southern
China: ecological implications, conservation and
environmental management. Regulated Rivers:
Research and Management 11:35-54.
Dunagan, C. 2008. Dam closer to coming down;
price for removal shoots up. Kitsap Sun. Available
online at:
http://www.kitsapsun.com/news/2008/feb/06/
dam-closer-to-coming-down-price-for-removal-up/.
Einsele, G., and M. Hinderer. 1997. Terrestrial
sediment yield and the lifetimes of reservoirs, lakes,
and larger basins. Geologische Rundschau
86:288-310.
Elm, A. 2004. En dammrivnings effekter flora
och fauna i och längs en å. Ljungaån, Marks
kommun. Thesis. Gothenburg University, Gothenburg,
Sweden.
Emanuel, K. 2005. Increasing destructiveness of
tropical cyclones over the past 30 years. Nature
436:686-688.
Ericson, J. P., C. J. Vörösmarty, S. L. Dingman,
L. G. Ward, and M. Meybeck. 2006. Effective sea-
level rise and deltas: cause of change and human
dimension implications. Global and Planetary
Change 50:63-82.
European Commission. 1992. Council Directive
92/43/EEC of 21 May 1992 on the conservation of
natural habitats and of wild fauna and flora.
European Commission, Brussels, Belgium.
European Commission. 2000. EU Water
Framework Directive 2000/60/EC of 22 December
2000 on integrated river basin management for
Europe. European Commission, Brussels, Belgium.
Evans, J. E., S. D. Mackey, J. F. Gottgens, and
W. M. Gill. 2000. Lessons from a dam failure. Ohio
Journal of Science 100:121-131.
Fearnside, P. M. 1997. Greenhouse-gas emissions
from Amazonian hydroelectric reservoirs: the
example of Brazil’s Tucurui Dam as compared to
fossil fuel alternatives. Environmental Conservation
24:64-75.
Gawley, B. 2008. Elwha dam removal project cost
rising to $308 million. Peninsula Daily News.
Available online at:
http://www.peninsuladailynews.
com/article/20080206/NEWS/802060303.
Gowan, C., K. Stephenson, and L. Shabman.
2006. The role of ecosystem valuation in
environmental decision making: hydropower
relicensing and dam removal on the Elwha River.
Ecological Economics 56:508-523.
Graf, W. L., editor. 2003. Dam removal research:
status and prospects. H. John Heinz III Center for
Science, Economics and the Environment,
Washington, D.C., USA.
Gregory, S., H. Li, and J. Li. 2002. The conceptual
basis for ecological responses to dam removal.
BioScience 52:713-723.
Hart, D. D., and N. L. Poff. 2002. A special section
on dam removal and river restoration. BioScience
52:643-738.
Hart, D. D., T. E. Johanson, K. L. Bushaw-
Newton, R. J. Horwitz, A. T. Bednarek, D. F.
Charles, D. A. Kreeger, and D. J. Velinsky. 2002.
Dam removal: challenges and opportunities for
ecological research and river restoration.
BioScience 52:669-681.
Hörnström, E. 2009. Plant recolonization
following dam removal: a phytometer experiment.
Thesis. Umeå University, Umeå, Sweden.
Jansson, R., C. Nilsson, M. Dynesius, and E.
Andersson. 2000. Effects of river regulation on
river-margin vegetation: a comparison of eight
boreal rivers. Ecological Applications 10:203-224.
Johnson, P. T. J., J. D. Olden, and M. J. Vander
Zanden. 2008. Dam invaders: impoundments
facilitate biological invasions into freshwaters.
Frontiers in Ecology and the Environment
6:357-363.
Kareiva, P., M. Marvier, and M. McClure. 2000.
Recovery and management options for spring/
summer Chinook salmon in the Columbia River
Basin. Science 290:977-979.
Kelly, C. A., J. W. M. Rudd, R. A. Bodaly, N. P.
Roulet, V. L. St. Louis, A. Heyes, T. R. Moore, S.
Schiff, R. Aravena, K. J. Scott, B. Dyck, R.
Harris, B. Warner, and G. Edwards. 1997.
Increases in fluxes of greenhouse gases and methyl
mercury following flooding of an experimental
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
reservoir. Environmental Science and Technology
31:1334-1344.
Kingsford, R. T. 2000. Ecological impacts of dams,
water diversions and river management on
floodplain wetlands in Australia. Austral Ecology
25:109-127.
Klein, C. A. 1999. On dams and democracy. Oregon
Law Review (Fall 1999). Abstract available online
at: http://papers.ssrn.com/sol3/papers.cfm?
abstract_id=1266162.
Kruse, S. A., and A. J. Scholz. 2006. Preliminary
economic assessment of dam removal: the Klamath
River. Ecotrust, Portland, Oregon, USA.
Laffaille, P., A. Acou, J. Guillouet, and A.
Legault. 2005. Temporal changes in European eel,
Anguilla anguilla, stocks in a small catchment after
installation of fish passes. Fisheries Management
and Ecology 12:123-129.
Laitila, T., A. Jonsson, and A. Paulrud. 2006.
Regleringsdammen vid Storsjö-Kapell. Sportfiskarnas
värdering av ett återställande till naturligt fjällfiske.
FjällMistra Report Number 19. FjällMistra, Umeå,
Sweden.
McCully, P. 2001. Silenced rivers: the ecology and
politics of large dams. St. Martin’s Press, New York,
New York, USA.
Morin, F. 2006. Vattenkraft samhällsekonomiskt
lönsamt? En studie om hur samerna, sportfisketurismen
och miljön påverkas av en vattenkraftsutbyggnad i
Kalixälven. Thesis. Luleå University of Technology,
Luleå, Sweden.
Nathanson, J. E. 1995. Malens (Silurus glanis)
reproduktions—och uppväxtplatser i Sverige samt
förslag till åtgärder för dess överlevnad.
Information från Sötvattenslaboratoriet Drottningholm
3:1-41.
National Park Service. 2007. National Park
Service awards contract for the Elwha water
facilities. Available online at:
http://www.nps.gov/
olym/parknews/national-park-service-awards-contract-
for-the-elwha-water-facilities.htm.
Nilsson, C., and K. Berggren. 2000. Alterations of
riparian ecosystems caused by river regulation.
BioScience 50:783-792.
Nilsson, C., R. Jansson, and U. Zinko. 1997.
Long-term responses of river-margin vegetation to
water-level regulation. Science 276:798-800.
Nilsson, C., C. A. Reidy, M. Dynesius, and C.
Revenga. 2005. Fragmentation and flow regulation
of the world’s large river systems. Science
308:405-408.
Orr, C. H., and E. H. Stanley. 2006. Vegetation
development and restoration potential of drained
reservoirs following dam removal in Wisconsin.
River Research and Applications 22:281-295.
Palmer, M. A., C. Reidy Liermann, C. Nilsson,
M. Flörke, J. Alcamo, P. S. Lake, and N. Bond.
2008. Climate change and the world’s river basins:
anticipating management options. Frontiers in
Ecology and the Environment 6:81-89.
Pess, G. R., M. L. McHenry, M. L., Beechie, T. J.
and Davies, J. 2008. Biological impacts of the
Elwha River dams and potential salmonid response
to dam removal. Northwest Science 82:72-90.
Provencher, B., H. Sarakinos, and T. Meyer.
2008. Does small dam removal affect local property
values? An empirical analysis. Contemporary
Economic Policy 26:187-197.
Rãdoane, M., and N. Rãdoane. 2005. Dams,
sediment sources and reservoir silting in Romania.
Geomorphology 71:112-125.
Rahel, F. J. 2007. Biogeographic barriers,
connectivity and homogenization of freshwater
faunas: it’s a small world after all. Freshwater
Biology 52:696-710.
Revenue Stream. 2008. An economic analysis of
the costs and benefits of removing the four dams on
the lower Snake River. Available online at:
http://w
ww.wildsalmon.org/index.php?option=
com_content&view-article&id=70.
RiverNet. 2008. The Saint Etienne de Vigan Dam
and the Maison Rouge Dam dismantled for Salmon.
European Rivers Network. Available online in: htt
p://www.rivernet.org/general/dams/decommissioni
ng_fr_hors_poutes/stedvig.htm.
Ruwitch, J. 2008. China rushes to fix dams; 9,000
sq miles flooded. Reuters AlertNet. Available online
at: http://www.alertnet.org/thenews/newsdesk/
PEK120395.htm.
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
Sarakinos, H., and S. E. Johnson. 2003. Social
perspectives on dam removal. Pages 40-55 in W. L.
Graf, editor. Dam removal research: status and
prospects. H. John Heinz III Center for Science,
Economics and the Environment, Washington, D.
C., USA.
Scudder, T. 2005 The future of large dams; dealing
with social, environmental, institutional and
political costs. Earthscan, London, UK.
Sethi, S. A., A. R. Selle, M. W. Doyle, E. H. Stanley,
and H. E. Kitchel. 2004. Response of unionid
mussels to dam removal in Koshkonong Creek,
Wisconsin (USA). Hydrobiologia 525:157-165.
Shafroth, P. B., J. M. Friedman, G. T. Auble, M.
L. Scott, and J. H. Braatne. 2002. Potential
responses of riparian vegetation to dam removal.
BioScience 52:703-712.
Shuman, J. R. 1995. Environmental considerations
for assessing dam removal alternatives for river
restoration. Regulated Rivers: Research and
Management 11:249-261.
Stanford, J. A., J. V. Ward, V. J. Liss, C. A.
Frissell, R. N. Williams, J. A. Lichatowich, and
C. C. Coutant. 1996. A general protocol for
restoration of regulated rivers. Regulated Rivers:
Research and Management 12:391-413.
Stanley, E. H., and M. W. Doyle. 2003. Trading
off: the ecological effects of dam removal. Frontiers
in Ecology and the Environment 1:15-22.
Stewart-Oaten, A., W. W. Murdoch, and K. R.
Parker. 1986. Environmental impact assessment:
“pseudoreplication” in time? Ecology 67:929-940.
St. Louis, V. L., C. A. Kelly, E. Duchemin, J. W.
M. Rudd, and D. M. Rosenberg. 2000. Reservoir
surfaces as sources of greenhouse gases to the
atmosphere: a global estimate. BioScience
50:766-775.
Sundberg, S., and T. Söderqvist. 2004. The
economic value of environmental change in Sweden.
Swedish Environmental Protection Agency Report
Number 5360. Swedish Environmental Protection
Agency, Stockholm, Sweden.
Swedish Board of Fisheries. 2008. Sik (Coregonus
lavaretus). Available online at:
http://www.fiskeriv
erket.se/vanstermeny/fiskochskaldjur/arter/allaarter/
sikcoregonuslavaretus.html.
Swedish Government. 2008. Available online at:
http://www.miljomal.nu/Environmental-Objectives-
Portal.
Swedish Meteorological and Hydrological
Institute (SMHI). 1994. Svenskt dammregister:
södra Sverige. Svenskt Vattenarkiv Number 55.
SMHI, Norrköping, Sweden.
Swedish Meteorological and Hydrological
Institute (SMHI). 1995. Svenskt dammregister:
norra Sverige. Svenskt Vattenarkiv Number 56.
SMHI, Norrköping, Sweden.
Syvitski, J. P. M., C. J. Vörösmarty, A. J. Kettner,
and P. Green. 2005. Impact of humans on the flux
of terrestrial sediment to the global coastal ocean.
Science 308:376-380.
University of Idaho. 2008. History of Elwha and
Glines Canyon dams. Elwha Watershed
Information Resource. Available online at:
http://w
ww.elwhainfo.org/elwha-river-watershed/dam-removal/
history-elwha-and-glines-canyon-dams.
U.S. Geological Survey. 2008. Magnitude 7.9—
Eastern Sichuan, China. Available online at:
http://
earthquake.usgs.gov/eqcenter/eqinthenews/2008/
us2008ryan/#details.
Vattenportalen. 2007. Vattenkraft och stora
dammar. Available online at:
http://www.vattenpor
talen.se/fov_problem_vattenkraft.htm.
Ward, J. V., and J. A. Stanford. 1995. Ecological
connectivity in alluvial river ecosystems and its
disruption by flow regulation. Regulated Rivers:
Research and Management 11:105-119.
World Commission on Dams (WCD). 2000. Dams
and development: a new framework for decisions-
making. Earthscan, London, UK.
Webster, P. J., G. J. Holland, J. A. Curry, J. A.
and H.-R. Chang. 2005. Changes in tropical
cyclone number, duration, and intensity in a
warming environment. Science 309:1844-1846.
Whitelaw, E., and E. Macmullan. 2002. A
framework for estimating the costs and benefits of
dam removal. BioScience 52:724-730.
Ecology and Society 14(2): 4
http://www.ecologyandsociety.org/vol14/iss2/art4/
World Wide Fund for Nature (WWF). 2004.
Rivers at risk: dams and the future of freshwater
ecosystems. WWF, Godalming, UK. Available
online at:
http://www.panda.org/downloads/freshwater/
riversatriskfullreport.pdf.
... Wolf reintroduction policies provide a typical example, and have led to controversies between ecologists and farmers in the eastern Germany, Scandinavia, and North America (Gross 2008; see also Keulartz 2009). River restoration is another focus of project attention, involving the removal of dams, river re-meandering and re-bouldering (e.g., in Sweden, see Lejon et al. 2009), 'daylighting' of culvert rivers, or ecological remediation of urban riverbanks (e.g., in the UK, see Eden and Tunstall 2006). ...
Article
Full-text available
Ecological restoration has taken on a new significance in the face of climate change and biodiversity loss. Despite its growing policy salience, however, the social and political sciences have paid limited attention to the study of ecological restoration policy and practice. By drawing upon the political science study of multilevel governance, institutions, power relations, and place-based politics, a flavour is given of what a political science engagement might contribute to the rich tapestry of analysis that has already been produced by other disciplines on ecological restoration. As the use of restoration grows, it is increasingly likely that it will give rise to social dispute and be brought into conflict with a variety of environmental, cultural, economic, and community interests. Restoration policy and projects encounter professional and institutional norms as well as place-specific interests and values. There is urgent need to investigate how and in what ways some interests become winners and others losers in these activities, and how this in turn can influence ecological restoration outcomes. A political science lens could help build new criteria for evaluating the success of ecological restoration, ones that combine both process- and product-driven considerations.
... The most common strategy is to restore the abiotic environment, hoping that the biota will recover as a result of this, which is usually referred to as the 'Field of Dreams' hypothesis (Palmer et al., 1997). This is manifested in restoration approaches such as re-naturalization of flows below dams (Tharme, 2003; Arthington, 2012; Nardini and Pavan, 2012), reconfiguration of channels (Roni et al., 2002; Shields et al., 2003) and dam removal (Bednarek, 2001; Lejon et al., 2009). In recent years, doubts have been raised whether ecological communities can recover by simply restoring their habitat. ...
Article
Full-text available
We reviewed follow-up studies from Finnish and Swedish streams that have been restored after timber-floating to assess the abiotic and biotic responses to restoration. More specifically, from a review of 18 case studies (16 published and 2 unpublished) we determined whether different taxonomic groups react differently or require different periods of time to respond to the same type of restoration. Restoration entailed returning coarse sediment (cobbles and boulders) and sometimes large wood to previously channelized turbulent reaches, primarily with the objective of meeting habitat requirements of naturally reproducing salmonid fish. The restored streams showed a consistent increase in channel complexity and retention capacity, but the biotic responses were weak or absent in most species groups. Aquatic mosses growing on boulders were drastically reduced shortly after restoration but in most studies they recovered after a few years. Riparian plants, macroinvertebrates, and fish did not show any consistent trends in response. We discuss seven alternative explanations to these inconsistent results and conclude that two decades is probably too short a time for most organisms to recover. We recommend long-term monitoring using standardized methods, a landscape-scale perspective, and a wider range of organisms to improve the basis for judging to what extent restoration in boreal streams has achieved its goal of reducing the impacts from timber-floating. This article is protected by copyright. All rights reserved.
... Recently, questions on the opportunity of dam removal and the ecological benefits of such restoration measures arise, but for specific contexts, the general rationale for restoring natural features often seems to get lost, and not only due to uses conflicts (Donnelly et al., 2002; Lejon et al., 2009). Often there is a local attachment to existing landscape features and scenery, but more importantly river managers encounter resistance of conservationist and fisheries stakeholders that question the potential gains and stress the risks of species loss. ...
Article
The formulation of scientifically justified guidelines for restoration and remediation of anthropogenic impacts on river health requires better understanding of the relationships between alteration and stream condition. Impoundment is one of the most widespread impairments of river systems around the world. The present study examines relationships between the presence and density of dams and biological metrics of river health in the context of a variety of environmental drivers over the Loire river basin. We hypothesized that dam density measured at supra-reach level would influence river health more significantly than the local level density, and further that the impact of dams is best estimated with measures for the functional organization of biotic assemblages. An extensive dataset of fish and invertebrate metrics (density of ecological guilds, and species richness) together with hydromorphological characteristics for 181 stream reaches in the Loire river basin was constructed and modelled with generalized linear models in order to quantify dam impact and investigate the importance of regional- and local-scale measures of dam density to the structure of biotic communities. The analysis showed that community structure at the basin scale responded significant to dam presence and confirmed that the strongest relationships were observed for specific functional trait-based metrics. For macroinvertebrates responses were stronger at higher scale level, and especially the upstream context explained on its own 70% of the observed impairment. For fish communities, the local context prevails and explained up to 70% of the dam impact. For the macroinvertebrates this observed impact counts up to 25% of the variance in the trait-based quality indices, whereas for fish communities the dam density only explains up to 12%. These results can be explained by the biotic processes ruling the specific groups, drift for the invertebrates and migrations between habitats for fish. The geographic context furthermore explains the differentiation in these responses, reflecting the metacommunity structure of invertebrate assembly over the river basin. We conclude that for upstream parts of the river basin, locally based management actions can be successful in restoring biotic integrity, whereas more downstream, dam removal actions require more integrated measures at catchment rather than local scale.
Article
Full-text available
Fish, especially migratory species, are assumed to benefit from dam removals that restore connectivity and access to upstream habitat, but few studies have evaluated this assumption. Therefore, we assessed the movement of migratory fishes in the springs of 2008 through 2010 and surveyed available habitat in the Little River, North Carolina, a tributary to the Neuse River, after three complete dam removals and one partial (notched) dam removal. We tagged migratory fishes with PIT tags at a resistance-board weir located at a dam removal site (river kilometer [rkm] 3.7) and followed their movements with an array of PIT antennas. The river-wide distribution of fish following removals varied by species. For example, 24–31% of anadromous American Shad Alosa sapidissima, 45–49% of resident Gizzard Shad Dorosoma cepedianum, and 4–11% of nonnative Flathead Catfish Pylodictis olivaris passed the dam removal site at rkm 56 in 2009 and 2010. No preremoval data were available for comparison, but reach connectivity appeared to increase as tagged individuals passed former dam sites and certain individuals moved extensively both upstream and downstream. However, 17–28% did not pass the partially removed dam at rkm 7.9, while 20–39% of those that passed remained downstream for more than a day before migrating upstream. Gizzard Shad required the deepest water to pass this notched structure, followed by American Shad then Flathead Catfish. Fish that passed the notched dam accessed more complex habitat (e.g., available substrate size-classes) in the middle and upper reaches. The results provide strong support for efforts to restore currently inaccessible habitat through complete removal of derelict dams.
Thesis
Full-text available
Sustaining freshwater ecosystems and responding to climate change are two of the greatest challenges facing humanity. Climate change and water are intimately linked: changes in climate affect hydrology, and societal responses to climate change (e.g. through mitigation and adaptation measures) affect water use. Thus, the management of climate change and water needs to be integrated to maximise benefits for people and nature conservation. This research asked 'What institutions and other tools can governments and societies most successfully apply, to integrate management of freshwater ecosystems?' To answer this question, the research examined management of freshwater ecosystems and climate change through different lenses, from the global to the local scales. At the international scale, the issue was explored from a 'new institutionalism' perspective, by systematically examining the key multilateral environment agreements adopted to manage climate change, biodiversity and water - the United Nations Framework Convention on Climate Change (UNFCCC), the Convention on Biological Diversity (CBD) and the Ramsar Convention on Wetlands. Documentary records from these regimes were examined for evidence of conflicts and positive synergies in policy integration, and the deployment of mechanisms for such integration. Each of these conventions requires national governments to integrate measures to achieve the objectives of the conventions into all appropriate sectoral institutions. This research showed that horizontal (at the same scale) and vertical (from global to local scale) integration mechanisms are missing, or poorly used. As a result, international climate change policies are having perverse impacts on freshwater ecosystems, and opportunities are being missed for positive, synergistic implementation of the three conventions. The papers presented here recommend responses that can improve such integration. At a national level, the research assessed national priorities and the state of integration of climate, energy, water and biodiversity policies from Australia, Brazil, China, the European Union, India, Mexico, South Africa, Tanzania and the United Kingdom. The sectoral silos identified were similar to those at the international scale. A framework for policy integration was used to assess legislation, coordination, leadership, and mechanisms for consultation and review. Numerous examples of negative impacts of climate change mitigation policies on freshwater ecosystems were identified, and few positive, synergistic measures were found. Developing countries had more holistic policies linking climate change adaptation and mitigation, whereas developed jurisdictions had conflated climate and energy policies. Little evidence was found of national governments either deploying tools that would aid conservation of freshwater ecosystems, or adopting measures to better enable subnational institutions to adapt to climate change. The research presented here recommends more systematic adoption of the better policy integration practices identified at the national scale. A number of long-standing measures for management of freshwater ecosystems were examined to see whether they continue to provide benefits for conservation as hydrology changes with the climate. The tools assessed were freshwater protected areas, environmental water allocations and periodic relicensing of water infrastructure. It was found that these measures have considerable benefits for freshwater conservation under climate change, can be applied now, and can be even more effective if modified to better account for the impacts of climate change. Empirical research undertaken at the local to basin scale assessed lessons from autonomous adaptation in river-basin management for more effective climate change adaptation. Six programs were assessed, from Brazil, China, India, Mexico, Tanzania and four eastern European countries along the lower Danube River. Eight main lessons were identified for more effective adaptation: providing multiple benefits; communicating opportunities for adaptation; promoting local ownership; providing immediate benefits; undertaking adaptive management; linking local, national and global institutions; providing consistent funding for adaptation; and seizing policy reform windows. The research found that national governments need to focus on facilitating adaptation through existing local institutions, especially through enabling laws, information and financing mechanisms. This work was supplemented with research on climate change adaption responses by governments in Australia's Murray-Darling basin. A number of responses to drought were identified as maladaption (both physically and as opportunity costs), because they were not sufficiently far-reaching for effective adaptation to climate change. At each scale, a framework of appropriate measures in legislation, leadership, horizontal integration, vertical integration, review and advisory mechanisms proved to be a robust framework for better management of freshwater ecosystems and climate change. While there are good-practice examples at all geopolitical scales, they are not often applied. Thus, at each scale, there are many opportunity for better integration and more positive, synergistic outcomes. It is clear that the large epistemological community and 'high politics' that has developed around climate change has a downside; that is, a limited engagement with other sectors. Hence, freshwater ecosystems and resources may be adversely affected by climate change both directly, as hydrology changes, and indirectly, through perverse impacts of mitigation and adaptation policies. Further research is needed to examine why international and national institutions have not better integrated their policies for management of freshwater ecosystems and climate change, to implement more sustainable solutions.
Article
Full-text available
Damming is one of the most widespread impairments of river systems around the world. The formulation of scientifically justified guidelines for restoration and remediation of impairments requires better understanding of the relationships between alteration and stream condition. The present study examines relationships between the presence and density of dams and biological metrics of river health in the context of a variety of environmental drivers over the Loire river basin. We hypothesized that dam density measured at supra-reach level would show more significant influence on river health than the local level density, and further that the impact of dams is best estimated with measures for the functional traits of biotic assemblages. An extensive dataset of fish (169 sites) and invertebrate (211 sites) communities in the Loire river basin, described with metrics of density of ecological guilds, taxonomic richness and life history traits, and coupled with reach hydromorphology and catchment characteristics was constructed. Generalized linear modeling was performed in order to quantify dam impact and investigate the importance of regional- and local-scale measures of dam density to the structure of biotic communities. The analysis showed that community structure at the basin scale responded significant to dam presence and confirmed that the strongest relationships were observed for specific functional trait-based metrics. For the macroinvertebrates the observed impact counts up to 25% of the variance in the trait-based quality indices, whereas for fish communities the dam density only explains up to 12%. Macroinvertebrate responses were stronger at higher scale level, and especially the upstream context explained on its own 70% of the observed impairment. For fish communities, the local context prevails and explained up to 70% of the dam impact. These results can be explained by the biotic processes ruling community assembly in the specific groups, passive dispersal for the invertebrates and migrations between habitats for fish. The geographic context furthermore explains the differentiation in these responses, reflecting the metacommunity structure of invertebrate assembly over the river basin. We conclude that for upstream parts of the river basin, locally based management actions can be successful in restoring biotic integrity, whereas more downstream, dam removal actions require more integrated measures at regional rather than local scale.
Book
Full-text available
Severe surface flow reduction is exacerbating the impacts of the existing stressors on aquatic ecosystems in southern Australia. River regulation via the creation of instream barriers such as dams and weirs is known to have wide ranging impacts on aquatic ecosystems and mitigating these barriers can greatly benefit aquatic fauna, particularly freshwater fishes. Given the continued reduction in surface flows and aging of barrier infrastructure, there will be an increasing need to assess, prioritise and decommission such structures particularly in southern Australia. Whilst considerable attention has been given to barrier mitigation and prioritisation in eastern Australia, there is less information on how barriers impact the ecosystems in the often intermittent rivers across southern Australia; particularly with regard to the relationship between barriers and refuge pools. There is also limited information on the impacts of complete barrier removal as opposed to barrier retrofitting and there is no consistent process for identifying and prioritising barriers for mitigation or removal across southern Australia. The current project aimed to review the global literature on the impacts of barriers and the processes that exist for prioritising their removal. It then aimed to develop and trial a process for instream barrier prioritisation tailored specifically for systems in southern Australian. Mitigation of instream barriers through the construction of fishways has been increasingly undertaken in Australia and internationally to reconnect fish communities however, whilst often partially effective, they are limited in terms of fully reconnecting fish communities and are also costly. Complete removal of barriers has therefore increasingly been undertaken particularly in the United States and Europe to completely reconnect river reaches. Both strong advocacy and opposition can exist to instream barrier removal projects and it is vital to have broad stakeholder involvement; particularly at a local level. Artificial instream barriers can also actually create important refuge habitats that may increase in significance particularly as surface flow reductions continue in southern Australia. However, spatial information on refuge pools across southern Australia is limited as are their relative ecological significance. Barrier prioritisation processes in Australia have usually utilised score and ranking systems but little regard has been given to optimising multiple barrier mitigations. The barrier identification and prioritisation process we developed is a stepwise protocol that is underpinned by broad stakeholder involvement and can be applied on multiple scales from single rivers to multiple catchments. It identifies existing information on barriers and aquatic fauna and also confirms barrier and refuge information using a cost-effective surveying protocol. It includes a score and ranking system that weights both the positive and potential negative impacts of removing instream barriers and incorporates information on species diversity, habitat availability, and spatial information on barriers and refuges. The process was trialled in three catchments in south-western Australia. Information on potential barrier locations and fish distributions was obtained by accessing GIS and distributional databases and undertaking local landholder surveys. The rapid aerial survey technique was found to be highly effective at confirming GIS information and identifying new barriers. The score and ranking system revealed that the least modified catchment had the highest scoring barriers. The information contained in this review will be of considerable interest to managers of fluvial ecosystems in temperate Australia and the prioritisation process will be a valuable and easily implemented tool in identifying and mitigating the impacts of in-stream barriers in southern Australia in a drying climate.
Article
Because of its generally low density of humans and few settlements, the circumpolar boreal forest is often viewed as an untouched wilderness. However, archeological evidence indicates that humans have inhabited the region since the continental glaciers disappeared 8,000-12,000 years ago. This paper discusses the ecological impacts that humans have had on the boreal forest ecosystem through their activities in prehistoric, historic, and recent times and argues that the boreal forest has always been a cultural landscape with a gradient of impacts both spatially and temporally. These activities include hunting, trapping, herding, agriculture, forestry, hydroelectric dam projects, oil and natural gas development, and mining. In prehistoric times, human impacts would generally have been more temporary and spatially localized. However, the megafaunal extinctions coincident with arrival of humans were very significant ecological impacts. In historic times, the spread of Europeans and their exploitation of the boreal's natural resources as well as agricultural expansion has altered the composition and continuity of the boreal forest ecosystem in North America, Fennoscandia, and Asia. Particularly over the last century, these impacts have increased significantly (e.g., some hydroelectric dams and tar sands developments that have altered and destroyed vast areas of the boreal forest). Although the atmospheric changes and resulting climatic changes due to human activities are causing the most significant changes to the high-latitude boreal forest ecosystem, any discussion of these impacts are beyond the limits of this paper and therefore are not included.
Article
Full-text available
Major rivers worldwide have experienced dramatic changes in flow, reducing their natural ability to adjust to and absorb disturbances. Given expected changes in global climate and water needs, this may create serious problems; including loss of native biodiversity and risks to ecosystems and humans from increased flooding or water shortages. Here, we project river discharge under different climate and water withdrawal scenarios and combine this with data on the impact of dams on large river basins to create global maps illustrating potential changes in discharge and water stress for dam-impacted and free-flowing basins. The projections indicate that every populated basin in the world will experience changes in river discharge and many will experience water stress. The magnitude of these impacts is used to identify basins likely and almost certain to require proactive or reactive management intervention. Our analysis indicates that the area in need of management action to mitigate the impacts of climate change is much greater for basins impacted by dams than for basins with free-flowing rivers. Nearly one billion people live in areas likely to require action and approximately 365 million people live in basins almost certain to require action. Proactive management efforts will minimize risks to ecosystems and people and may be less costly than reactive efforts taken only once problems have arisen.
Article
Full-text available
There may be problems concerning the appropriate design of sampling programs to assess the impact upon the abundance of biological populations of, for example, the discharge of effluents into an aquatic ecosystem at a single point. Key to the resolution of these issues is correct identification of the statistical parameter of interest, which is the mean of the underlying probabilistic 'process' that produces the abundance, rather than the actual abundance itself. An appropriate sampling scheme was designed to detect the effect of the discharge upon this underlying mean. Detection of the effect of the discharge is achieved by testing whether the difference between abundances at a control site and an impact site changes once the discharge begins. -from Authors
Article
Full-text available
Romania ranks among countries with the greatest achievements in the field of dams in the world. Among the 80 membership countries of the ICOLD, Romania ranks 19th in “large dams” and the 9th in Europe. The reservoirs arranged behind dams are characterised by small capacities, generally under 200 million mc. The total number of big dams is 246, among which almost half are dams under 40 m in height. The highest dam is Gura Apelor, on Râul Mare, in the Retezat Mountains and it is 168 m. We can add to these other 1500 dams, under 15 m in height, with the reservoirs having capacities under 1 million m³. The anthropic intervention through the arranging of dams and reservoirs in the river systems of Romania's territory is significant and justifies the concern of geomorphologists to know the relations between the dynamics of the landscape and the behaviour of these anthropic structures.
Book
This book explains the history and politics of dam building worldwide. It describes the many technical, safety and economic problems that afflict the technology, and explores the role played by international banks and aid agencies in promoting it. The author also examines the rapid growth of the international anti-dam movements, and stresses how replacing large dams with less destructive alternatives will depend upon opening up the dam industry's practices to public scrutiny.
Article
Viewed by some as symbols of progress and by others as inherently flawed, large dams remain one of the most contentious development issues on Earth. Building on the work of the now defunct World Commission on Dams, Thayer Scudder wades into the debate with unprecedented authority. Employing the Commission's Seven Strategic priorities, Scudder charts the 'middle way' forward by examining the impacts of large dams on ecosystems, societies and political economies. He also analyses the structure of the decision-making process for water resource development and tackles the highly contentious issue of dam-induced resettlement, illuminated by a statistical analysis of 50 cases.
Article
The IVEX Dam (Chagrin River, northeastern Ohio) failed catastrophically on 13 August 1994, releasing 38,000 m3 (about 10 million gallons) of impounded water and sediment. This event was triggered by a 70-year rainfall event (13.54 cm of rainfall within 24-hours), resulting in flows 1.9 m above the top of the spillway and impinging on the top of the dam. The failure was the result of seepage piping at the toe of the dam, near the masonry spillway-earthen dam contact. Eyewitnesses reported that collapse of the seepage pipe created a breach in the dam that rapidly downcut. Paleohydrologic modeling suggests peak discharge through the breach was about 466 m'sec"1, substantially dewatering the reservoir in approximately 2-3 minutes. The effects of failure included erosion, flooding, and sedimentation downstream, and erosion of fine-grained sediment within the reservoir itself. Of the accumulated reservoir sediment, 9-13% was mobilized by dam breach and consequent incision (as the Chagrin River re-established its gradient by downcutting through reservoir sediment). Of this amount, 61-86% was trapped in a downstream reservoir (threatening the integrity of this structure). The failure of this dam can be attributed to a large hydrologic event and the combination of several factors: 1) inadequate spillway design, 2) lack of an emergency spillway, 3) 86% loss of permanent pool capacity due to 152 years of sedimentation, and 4) poor dam maintenance resulting in seepage piping failure. Similar dam failures will become an increasing societal problem, due to the aging of the nation's 75,591 larger dams and reservoirs, of which 95% are privately owned and operated.