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Ice Jam flooding on the lower Mohawk River and the 2018 mid-winter ice jam event

Conference Paper

Ice Jam flooding on the lower Mohawk River and the 2018 mid-winter ice jam event

Abstract and Figures

An ice jam of historic proportions formed in January 2018 on the lower Mohawk River. The ice jam was 27 km long, and the toe was lodged in the Rexford Knolls, a chronic jam point. The Knolls are a unique section of the river where late-glacial capture moved the channel to a bedrock incised gorge, and today the channel is narrow and deep with a prominent constriction. Along the length of the jam at least four other jam points also affected flow and progress of ice movement. The toe of the jam failed during high water at 21-22 February caused by rain and then exceptionally warm temperatures (21°C, 70°F). A significant release of water moved downstream, and water levels dropped 1.8 m (6 ft) in a few hours, which relieved flooding of homes in the Stockade of Schenectady.
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Ice Jam flooding on the lower Mohawk River and the 2018 mid-winter ice jam event
John I. Garver
Geology Department, Union College, Schenectady, NY
An ice jam of historic proportions formed in January 2018 on the lower Mohawk River. The ice jam was
27 km long, and the toe was lodged in the Rexford Knolls, a chronic jam point. The Knolls are a unique
section of the river where late-glacial capture moved the channel to a bedrock incised gorge, and today the
channel is narrow and deep with a prominent constriction. Along the length of the jam at least four other
jam points also affected flow and progress of ice movement. The toe of the jam failed during high water at
21-22 February caused by rain and then exceptionally warm temperatures (21°C, 70°F). A significant
release of water moved downstream, and water levels dropped 1.8 m (6 ft) in a few hours, which relieved
flooding of homes in the Stockade of Schenectady.
The event. The rapid thaw and rain on 12 Jan 2018 caused the ice in the lower Mohawk River to break up
on the morning of 13 January, and most of the activity was concentrated in the Schenectady pool between
Lock E8 and Lock E7. Initial breakup caused a jam and blockage between the GE outfall and Lock 8 (Isle
of the Oneidas) with significant back up (maximum differential of about 3.4 m or 11 ft) at about 10:30 AM:
sheet ice extended from the front of the jam (near GE) to Lock 7 (nearly 10 mi or 16 km). This first jam
broke at 1030 AM, released a surge, and this ice and additional upstream ice formed a second jam in the
Rexford Knolls by about 1220 PM. By late afternoon, the back up (differential) between Rexford (in the
ice floe, behind the jam point) and Vischer (down river) was between 1.8 and 2.1 m (6 and 7 ft). This jam
had an estimated length of 19 km (~12 mi) (solid packed ice from the Knolls to the Mabee Farm). This jam
would be in place for over a month.
This jam remained in place following crest on the Mohawk, but rain and snow melt the following week
caused renewed concern that the jam would be mobilized between 24-25 January. The jam did not move,
because crest on the Mohawk (25 Jan, ~19K cfs at Cohoes), was lower than the initial event (13 Jan, 21-
23k cfs). However, in this second event, release of ice from the Schoharie Creek worked down river and the
jam grew significantly in length (8 km, ~5 miles), the total length of the jam was then 27 km (17 mi) long,
extending from the Knolls to near Lock 10 (Wolf Hollow-Swart Hill Road). Moderate temperatures in the
next few weeks resulted in the significant loss of ice.
Rain on 19 Feb and very warm temperatures on 20 and 21 Feb resulted in remobilization of ice at the up
river end (on 20 Jan), and then after considerable back up flooding (between 10 and 15 ft or 3.0 to 4.6 m),
especially in the Stockade (maximum of 225 BCD or 223.8 NAVD). Finally, the original toe of the jam
broke at 0200 AM in 22 February, and stage measurements and eyewitness accounts suggest that a
movement of E9/Mabee jam (at the back end of the system) at 0100 AM sent a release wave that drove
failure at the toe. Once the entire lower part of the jam release, a surge of water went down river to Cohoes
(maximum discharge of 50 k cfs), and two smaller jams remained in place after breakup. The more
significant of these was at Lock 8, which was 4.8 km (3 mi) miles long, longer in part due to additional ice
from the Lock 9/Mabee jam.
Background. Ice jams are chronic in the Schenectady pool on the lower Mohawk River in eastern NY
State (Lederer and Garver, 2001; Scheller and others, 2002; Garver and Cockburn, 2009; Marsellos and
others, 2010; Garver, 2014; Garver and others, this volume). The lower part of the Mohawk River has a
low gradient, and the permanent dam at Vischer’s Ferry (also Lock E7) impounds water for nearly 16 km
(~10 miles) to Lock E8, and thus this is one site where thick sheet ice builds in the winter. Several
constrictions in the river channel and floodplain - both natural and man-made - reduce surface area and
potential flow at high water. The Rexford Knolls is a natural constriction that occurs between the Rexford
Bridge (Rt. 146) and Vischer’s Ferry Dam. This section of the river is incised deeply into bedrock and it
has essentially no floodplain: here it is bound by steep cliffs, and the channel is very deep (in excess of 12
m). The Knolls are a chronic jam point, and recent jams occurred in the same location, and this was also a
jam point the 1914 event, the worst historical ice jam ever in this region (see summary in Garver, 2014).
Garver, J.I., 2018. Ice Jam flooding on the lower Mohawk River and the 2018 mid-winter ice jam event. In: Cockburn, J.M.H.
and Garver, J.I., Proceedings from the 2018 Mohawk Watershed Symposium, Union College, Schenectady NY, 23 March
2018, v. 10, p. 13-18
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Most ice jams on the lower Mohawk form when warm temperatures and significant discharge drive the
disintegration of river ice, especially sheet ice, which can thick on impounded sections of the River. The
Mohawk River in the Schenectady area is troublesome because the gradient is low, there are a number of
constrictions, and commonly covered thick sheet ice because it is an impounded pool (impeded by the
Vischer’s Ferry Dam). In this section, water depth varies, and several key sections of the River are
relatively deep, so that water moves more slowly in higher flow conditions. In the past decade have been
seeing a number of mid-winter break up events, which are complicated if the system is incompletely
flushed.
Jams form when a rapid influx of runoff increased discharge and moving ice in the channel becomes
impeded. In almost all historical observations on the Mohawk, ice jams occur early in the hydrologic event
as water levels are rising. During break up and down-river ice movement, the process can be orderly and
uneventful if no obstructions and blocking occur. But ice floes can, and typically do, get jammed and can
cause restriction of flow on the river. Several factors promote jamming. One is a change in down-river
gradient because low gradient (or flat) water moves more slowly, so a simple change in flow rate can
initiate blockage and jamming. Another is constrictions and blockage that can restrict flow that can lead to
thickening and ultimately damming of flow. The Schenectady pool between Lock E8 and Lock E7 has
both.
Locks and dams. This section of the Mohawk is part of the Erie Canal, and there are a series of locks and
dams along the length of this study area. Almost all of the dams at the locks are removable, and swing
upwards in the winter. A critical exception is the 30 ft (9.1 m) high Vischer’s Ferry dam (Lock E7), which
is classified as a NYS Class C, high hazard dam. This dam creates the Schenectady pool, which extends for
10 miles between Lock E7 and Lock E8. This section of the River has a low gradient and has significant
sheet ice in the winter. The channel is very deep in the Knolls and there are several important constrictions
where channel width is reduced by nearly a factor of two. Thus, ice jams form in this reach of the Mohawk
almost every year. Thus for those who study the hazard of ice jamming on the Mohawk, there is little
question that the pooled water behind permanent Vischer’s Ferry dam is a major contributing factor to ice
jams and ice jam flooding.
Figure 1: Map of key features related to ice jamming on part of the lower Mohawk River (NY) after 28 Jan
2018. The toe of the jam released on 22 February, and much of the jam below the Stockade went
downriver. Erie Canal locks (E7, E8, E9, E10) are marked.
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Jams can cause dams that block flow and these can result in spectacular changes in water levels. When
damming occurs, flooding can result in an up-river rise in water elevation (stage), and that rise can be very
rapid, especially if the river flow is blocked. Rise in stage elevation between 3 and 5 m (~10 and 15 ft) in
several hours have been recorded during the last significant events in 2007 and 2010 (Garver, 2014). As
water rises behind a dam, ice consolidates and adjusts, but because ice floats the blockage can be self-
destructive and this rising water can promote failure of the ice dam. This rapid rise presents a challenge for
Emergency Management because often it is unclear how rapid the water rise will be and if the ice dam will
fail.
When a dam breaks, a release wave (or ice jam release surge) propagates down river and this wave can
promote more jamming and damming, or simply proceed down river in an uneventful way. Release waves
can involve an enormous amount of water, and they too can cause a spectacular rise in water level. Long-
term monitoring of stage and discharge on the Mohawk by the USGS shows that many of the highest flows
(discharge) recorded on the Mohawk at Cohoes Falls have been directly related to release waves. In the
last 50 yr, the two largest recorded peak instantaneous flows 1996 and 1964 were release waves from
failed ice jams up river (see Figure 3, and Garver, 2014).
Channel width and depth are important when considering jam points. Changes in the channel width may
result in constriction points that can force jamming due to bottlenecking. The channel width varies wildly
depending on stage elevation, partly because at high stage elevations the water spreads out across the flood
plain. Here the channel width at relatively low flow when ice jamming is initiated has been estimated for
the actively used channel in the 2018 event. Several reaches of the River have significant reductions in
effective channel width, and one of the more prominent is the one in the Rexford Knolls (at KAPL), where
the width is reduced by ~60%. Channel depth matters because deeper water moves more slowly, and hence
can promote ice jamming due to surface velocity change. The channel depth between E7 and E8 is
variable, partly due to modification for navigation, but the deepest part is in the bedrock-lined section
through the Knolls (Fig 3, GE R&D).
Figure 2. Estimate of effective channel width used by the river during the initiation of ice out events.
Channel widths were measured only on active channels, and in some instances where channel bifurcate,
only one has rubble ice and significant flow. The two best known jam points in the lower Mohawk are at the
Isle of the Oneidas, and in the Knolls (Knolls Atomic Power Laboratories or KAPL above) where the river
channel narrows significantly. Dotted line is a simple polynomial through the data.2
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Figure 3: Effective channel depth on the Mohawk River from Lock E8 to Vischer’s Ferry (Lock E7) shown
in feet. Depths are maximum depths with a river level of a 10 yr flood. Channel profile from the
Schenectady County Flood Insurance Study (FEMA). The deepest section is in the Knolls, a section of the
river with no floodplain and steep bedrock walls. Black stars indicate the location of sensors in the
network.
Ice jams are particularly problematic for Emergency Management because change can occur quickly and
damage can be severe. One challenge is that backed up water behind a dam (back up flooding) can rise
(and fall) remarkably fast, and the rate of change complicates the decision making for evacuation and
securing river-proximal assets. Another reason is that the surge of the release wave (release wave surge)
can also result in rapid and significant rises in water levels. While some reaches of the river may be prone
to jamming and back up flooding, downstream communities may need to understand and appreciate the
timing of release waves, the amount of water released, and the velocity of the wave.
Figure 5. Comparison of hydrographs for specific events with ice jams on the lower Mohawk River.
Discharge records downriver at Cohoes show an abrupt decrease in flow, followed by surge. The decrease
in flow is related to upstream damming and blockage by ice, and the surge represents the ice jam release
wave (two jam events are record in 1964 and 1996, but only a single jam in 2007 and 2010, and 2018A,B).
The release wave was particularly dramatic in the 1964 event, and this is the highest instantaneous
discharge ever (directly) on the Mohawk. The initial 2018 event (13 Jan) was driven by a very small event,
and the release wave for the breakup of the jam (22 Feb) occurred after crest.
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Real-time data. Because this section of the Mohawk River has chronic ice jams, the US Geological
Survey (USGS) has installed an ice jam monitoring system between Lock E8 and Lock E7 (Vischer Ferry
Dam). This system consists of four stream gages for the rapid determination of stage elevation (river
elevation), and data are transmitted by GOES satellite and are then available in near real time on the
internet (Wall and others, 2013).
Release Wave. The release of water from ice dam breaks are of critical importance in emergency
management, but we have little
data on how these waves
propagate down river in the
Mohawk. A small release wave
occurred in the initial event, and
the nature of the wave provides
important information about
waves in this part of the
Mohawk. The increase in stage
elevation from the release wave
from the first jam (13 Jan) can be
seen in the down river gages (Freeman’s Bridge, Rexford, Vischer Ferry, and then eventually at Cohoes
Falls near the confluence with the Hudson River).
Arrival calculations suggest that the release wave on 13 January travelled at ~20 km/hr (12.4 mph, or 5.5
m/s). As is well known in the literature, the waveform gets attenuated down river from the release point,
and this results in a decrease in velocity, amplitude, and wavelength (Belatos, 2005; 2017). Thus the
integrated celerity (velocity) is estimated to be 24 km/hr (15.2 mph or 6.7 m/s) for the release wave to
Vischer’s Ferry. Note that these calculations are for the celerity (velocity) of the leading edge of the wave
(CL), which is the fastest moving part of the wave (Belatos, 2005).
The release wave continued down river and was recorded by an increase in stage elevation at Cohoes Falls
near the Hudson River. The travel time can be used to estimate an integrated down-river velocity of
between 18.6 and 20.3 km/hr (11.6 to 12.6 mph or 5.2 to 5.6 m/s). In the 2010 Ice jam release initiated
between Lock E8 and Lock E9, a large and significant release wave left Rotterdam Junction and arrived in
Cohoes travelling at an average celerity of 19.5 km/hr (12 mph or 5.4 m/s) (Garver, 2014 see Figure 2).
These numbers can guide alerts and warnings if we know a large and significant release has occurred and is
moving down river.
Figure 7: Down river arrival of the main release wave on 13 January that originated from the Lock 8 area
(between E8 and GE outfall). [A] Wave surge in the ice floe; [B] Wave estimates from only down river of
the toe of the ice jam. This wave travelled down river and the successive arrival times at sensors allow for
estimation of the velocity of the wave, which here is calculated to be approximately 18.6 and 20.3 km/hr
(11.6 to 12.6 mph see Table 1). The wave was attenuated downstream (Data: USGS Cohoes, unverified
data).
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Summary. This break up event resulted from a thaw with rain, and it was preceded and followed by
extremely cold weather and freezing. In mid January a jam formed, dammed, released, and subsequently
became lodged in the confined and narrow Rexford Knolls, a chronic jam point. This section of the river is
deep, and there is a prominent constriction in the effective channel width. It is also in a static pool that is
impounded by the Vischer’s Ferry dam, hence this is a location where a significant amount of strong sheet
ice forms in the winter months. A subsequent thaw on 24-25 January did not result in movement of the floe,
but additional ice was added to the tail so that the length surpassed 17 miles. On 22 February another rapid
thaw resulted in the released of the jam, but only after it caused considerable flooding in the historic
Stockade district of Schenectady.
References
Beltaos, S., 2017. Hydrodynamics of storage release during river ice breakup. Cold Regions Science and
Technology, 139, pp.36-50.
Beltaos, S., 2005. Field measurements and analysis of waves generated by ice-jam releases.
In Proceedings, 13th Workshop on the Hydraulics of Ice Covered Rivers, Hanover, NH (pp. 227-249).
Garver, J.I., 2014. Insight from Ice Jams on the Lower Mohawk River, NY. In Cockburn, J.M.H. and
Garver, J.I., Proceedings of the 2014 Mohawk Watershed Symposium, Union College, Schenectady, NY,
p.12-15
Garver, J.I., and Cockburn, J.M.H. 2009. A historical perspective of Ice Jams on the lower Mohawk River.
In: Cockburn, J.M.H. and Garver, J.I., Proceedings from the 2009 Mohawk Watershed Symposium, Union
College, Schenectady NY, p. 25-29.
Garver, JI, Capovani, E, and Pokrzywka, 2018. Photogrammetric models from UAV mapping and ice
thickness estimated of the 2018 mid-winter Ice jam on the Mohawk River, NY (this volume).
Lederer, J.R., and Garver, J.I., 2001, Ice jams on the lower Mohawk River, New York: Lessons from recent
breakup events. Geological Society of America, Abstracts with Programs v. 33, n. 1, p. 73.
Marsellos, A.E., Garver, J.I., and Cockburn, J.M.H., 2010, Mapping and Volumetric calculations of the
January 2010 Ice Jam Flood, Lower Mohawk River, using LiDAR and GIS; Cockburn, J.M.H. and Garver,
J.I., Proceedings of the 2010 Mohawk Watershed Symposium, Union College, Schenectady, NY, March
19, 2010, p. 23-27.
Scheller, M., Luey, K., and Garver, J.I., 2002. Major Floods on the Mohawk River (NY): 1832-2000.
Retrieved March 2014 from http://minerva.union.edu/garverj/mohawk/170_yr.html
Wall, G., Gazoorian, C. and Garver, J.I., 2013, March. USGS Ice jam and flood monitoring: Mohawk
River, Schenectady, in Proceedings of the 2013 Mohawk Watershed Symposium, Union College,
Schenectady, NY, p.83-85.
Invited Presentation
... Observations from the Northeastern US [22] also propose that the short duration and low intensity of cold periods combined with dominant above-freezing temperatures and more frequent rain events are preventing the formation of a complete ice cover at an increasing number of locations and, as a consequence, breakup scenarios are becoming more thermal. However, intense ice jam events are still happening in watersheds located just south of Quebec, especially during the mid-winter period [23,24]. In addition, and although the climate transposition may not be as representative, it was found, using empirical thresholds, that mid-winter and spring breakup ice jams in Midwest US were becoming less frequent, but potentially more intense [25]. ...
... The extent of this information helped define the number of municipalities included in the study (Table 1). The structure of each ice breakup model is the same that was presented for the Montmorency River [23]. The model uses degree-days (DD) as a breakup resisting indicator and the estimated discharge (Q) as a breakup driving indicator. ...
... The structure of each ice breakup model is the same that was presented for the Montmorency River [23]. The model uses degree-days (DD) as a breakup resisting indicator and the estimated discharge (Q) as a breakup driving indicator. ...
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... Ice jam floods are frequent occurrences along the Lower Mohawk River, especially during the spring breakup period, although mid-winter breakup jams can also occur (Garver, 2018). Severe ice jams cause extensive flooding, ice damage, and other socioeconomic losses. ...
... Boundary conditions (Figure 2) are the stages at Fonda and the Vischer Ferry Dam and the Schoharie Creek discharge, based on the USGS gauging station data of the 2018 ice jam event. The simulated result agrees with the typical ice and jamming process observed (Garver 2018). The simulation assumes the entire river domain was ice-covered, except for a short reach upstream of Lock 12, based on the Satellite image on Jan. 6, 2018. ...
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The 12th Mohawk Watershed Symposium was cancelled due to Covid-19. This abstract volume, which was essentially complete at the time of cancellation, is the record of the meeting that did not happen. Over the years this Symposium has taken on an important role in unifying and galvanizing stakeholders in the watershed. A coalition of invested stakeholders allows us as a group to tackle important issues that affect water quality, recreation opportunities, flood mitigation, and other basin-wide issues. By all measures, 2019 was a big year in the watershed. The historic 2019 Halloween Storm caused significant damage in the upper part of the watershed, especially in the West Canada Creek, East Canada Creek, and a number of smaller tributaries. Aid from FEMA for individual assistance was denied and this has caused considerable distress for those with damaged homes. A major effort this year was the work of the Reimagine the Canal task force. 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The Federal Energy Regulatory Commission (FERC) license is coming up, so NYPA, the dam owner, started the renewal process last year for both the VFD and the Crescent Dam, just downstream. The FERC review process can force significant environmental review of the ways in which dams integrate into the local ecosystem and relate to river hydrology. Meanwhile, the City of Schenectady continues formulating its ambitious plan to use FEMA funds to mitigate flooding in Stockade. The plan moving forward may involve elevating or perhaps moving homes in a managed retreat. This plan is intertwined with mitigation efforts for ice jamming at the VFD because jamming causes back-up flooding that can affect the Stockade. Water quality remains a central issue in the watershed and a growing number of stakeholders are involved in this effort. For a healthy and vibrant ecosystem we need clean water. 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A midwinter thaw on 23 to 25 January 2019 resulted in ice jams on the lower Mohawk River. As in the past, a significant fraction of the ice on the main stem of the Mohawk got caught up and jammed above Lock E7: for the majority of this event, no rubble ice went over the Vischer Ferry dam, and thus tens of miles of river ice had become imbricated and concentrated in this lower stretch of the River. Most ice jamming occurred between Lock 9 (Rotterdam Junction) and Lock 7 (Vischer Ferry Dam), and thus the main activity was focused between Rotterdam Junction, Glenville, Scotia, Schenectady, and Niskayuna. Because this stretch of the River has chronic ice jams, the USGS has installed an ice jam monitoring system, which involves four closely spaced stage gauges (5 min data) and four real-time cameras. Primary jam points identified in this event are significant constrictions in the river channel: 1) the Rexford Knolls; 2) Freeman’s Bridge area; 3) Isle of Oneida’s and Isle of Onondaga’s; and 4) Mabee Farm. We are unable to demonstrate significant blockage by any bridge or abutment in this event: only channel constriction. As in the past several prominent ice jams were emplaced, and then remained stuck until later floodwater floated the ice and forced failure. Once a jam in in place, the stage of emplacement must be reached or exceeded to mobilize previously jammed ice. Release waves are common once jammed ice moves and pressure is released. Unimpeded Release waves travel down river for tens of kilometers at velocities that are a function of wave celerity and river speed (here 3.3 m/s – 7.4 mph). Release waves that encounter In situ jams are significantly impeded by the thick ice floes, but the wave can also dislodge jams, which occurred in the 2018 jam (Garver, 2018). We hypothesize that the two most significant jam points are caused by sediment infill affecting the effective channel width. Below E8, only the south channel is active around the Isle of the Oneidas and this is undoubtedly due to sediment infilling in the north channel that received a tremendous load of sediment during Irene (2011) due to failure and breach around E8 (north side breach). In the Knolls water has been more of less static since establishment of the Vischer Ferry dam in 1916. Sediment accumulation and the development shallows on the north side of the river has reduced the effective channel width, thus forcing ice jamming. Sediment infill at these two chronic jam sites could be easily removed to remediate this ice jam hazard. Ice jams on the lower Mohawk River are caused by channel constriction. In the last two years significant mid-winter jams have formed and lodged below Lock 8, and in the Rexford Knolls. In both cases there is a dramatic reduction in the effective channel width, and that reduction causes lateral shoving, imbrication, and thickening that promotes jamming. It is likely in both cases that channel reduction is affected by significant accumulation of sediment in the channel, and removal of that sediment may go a long way to alleviating the ice jam hazard in this area.
Conference Paper
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This is the abstract volume of the 11th Mohawk Watershed Symposium. Over the years this Symposium has taken on an important role in unifying and galvanizing stakeholders in the Basin. A coalition of concerned and invested stakeholders allows us as a group to tackle important issues that affect water quality, recreation opportunities, flood mitigation, and other basin-wide issues. This was a big year in the watershed with a number of important developments that centered on floods, dams, water quality, and stewardship. With another ice jam on the lower Mohawk River this winter, we were again reminded of the susceptibility of low-lying communities to flooding. A new initiative from the State seeks to get to the root cause of how, why, and where ice jams form, and perhaps what can be done about this hazard. Meanwhile the City of Schenectady has embarked on an ambitious plan to mitigate flooding in Stockade, the first historic district in the State of New York. A key to watershed management is our water infrastructure. The primary components of concern are dams and sewage systems and to a lesser extent transportation networks. Dams in the Watershed are used mainly for drinking water, canal supply, and hydropower. The Watershed has nearly 100 NYS Class C and Class B (high-hazard and intermediate-hazard ) dams, and hundreds of smaller Class C and D dams. We have a number of dams that are critical for drinking water, and the Gilboa Dam on the upper Schoharie Creek is a wonderful example: the recent major rehabilitation of the Gilboa dam resulted not only in dam strengthening and hazard reduction, but also provided changes that include a low-level outlet that can be used for conservation releases to sustain the downstream ecosystem in the summer. For dams that generate hydropower, the Federal Energy Regulatory Commission (FERC) issues licenses based on power generation, energy conservation, protection of fish and wildlife, preservation of recreational uses, and general environmental quality. As a result, the FERC review process can force significant environmental review of the ways in which dams integrate into the local ecosystem. Thus when dams come up for review, stakeholders have an important responsibility to get involved and have their voices heard. FERC reviews of the Blenheim-Gilboa Dam (on the Schoharie Creek) and the West Canada Creek Hydroelectric Project (on the West Canada Creek) have recently generated intense interest by local stakeholders. Some of the focus has been on not only how the dams are integrated into the ecosystem, but also how they are integrated into the fabric of local communities. Some dams have outlived their utility, and these dams should be removed both for the benefit of the local ecosystem and for the safety of those living downstream. Given the industrial heritage in the Mohawk Valley, it is not surprising that there are a number of abandoned dams that no longer serve their original functions. We know that dam removal can have tremendous positive impact on fish passage and the local ecology, but we also know that removal can be an expensive and involved process. Facilitation of fish passage is a primary driver in dam removal, although we have learned that it inevitably results in passage both by species that belong in this watershed and by invasive species, illustrating the point that some barriers are useful. Water quality remains a central issue in the Watershed. For a healthy and vibrant ecosystem we need clean water. We know that locally our waterways are impaired, and the indicators include pathogens and plastics. We now understand the health of our waters from hundreds of measurements taken across the watershed by students, educators, and dedicated professionals from SUNY Cobleskill, SUNY IT Polytechnic in Utica, Union, Cornell, Schoharie River Center, Riverkeeper, DEC, USGS, and others who have been addressing water quality through research. These critical measurements include quantifying the distribution, source, and fate of environmental contaminants including fecal bacterial, microplastics, nitrogen, phosphorus, and other compounds that affect water quality. Stewardship and education are a critical piece of effective watershed management. Stakeholder meetings like the Mohawk Watershed Symposium, and local water advocates (including West Canada Creek Alliance, Riverkeeper, and Dam Concerned Citizens) play a key role in identifying problems, educating the public, and effecting change where it is most needed. Youth education programs centered on water quality and ecosystem health, such as the Environmental Study Teams at both the Schoharie River Center and Fort Plain High School, insure that all our waterways pass into the hands of the next generation of active, engaged, and knowledgeable stewards. The Mohawk River Basin has a new Action Agenda and Watershed management plan. In 2009 the first plan was developed by NYS DEC and partners, and the new five-year plan (2018-2022) was completed at the end of last year (2018) and will be released here at the Symposium. The overall goal is consistent with the whole-Hudson approach of a swimmable, fishable, resilient watershed. There are four main goals of the plan: 1) Improve water quality; 2) improve fisheries and wildlife habitat; 3) reduce flood risk and build resilient communities; and 4) create and foster stewardship opportunities. This is our new plan, and you, as a stakeholder, should be part of making it successful. Our keynote speaker is Hon. Rep. Antonio Delgado, a native of Schenectady, who represents the 19th Congressional District. The 19th District is one of the largest in New York State, and it includes a wide swath of the Catskills, including the Schoharie Creek, part of the Mohawk, and a large section of the Hudson from the Capital District south to Poughkeepsie. In the short time he has been in Congress Rep. Delgado has demonstrated a commitment to our water infrastructure. He is founding member of the bipartisan Congressional PFAS Task Force, and he is a co-sponsor of the Water Affordability, Transparency, Equity and Reliability Act (WATER Act) of 2019. He serves on the House Agriculture Committee, the House Committee on Transportation and Infrastructure, and the Small business Committee. This year’s meeting features 30 presentations that cover a wide range of topics. We hope that the selection of talks and posters will shape the discussion and continue the conversation about issues within the basin. By the end of the day, the Mohawk Watershed Symposium series will have been the forum for 340 talks, posters, and special presentations since its inception in 2009. Thank you to all who have participated. New York City water supply and infrastructure upgrades at Schoharie Reservoir A. Bosch p. 1 The New York State Mesonet: Providing real-time, high-quality environmental information across the Mohawk watershed J. Brotzge, C. Thorncraft, J. Wang p. 3 Toward improved community resiliency: Developing and assessing ice jam and flood mitigation measures along the Mohawk River M. Carabetta, J. MacBroom, J. Gouin, R. Schiff, B. Cote p.5 Characterization of disinfection by-product formation potential in Mohawk River source waters to support TMDL implementation A. Conine, M. Schnore, Z. Smith, G. Lemly, C. Stoll, A.J. Smith p. 6 The Mohawk River Basin Action Agenda 2019-2023: A Five-Year Plan for a Swimmable, Fishable Mohawk K. Czajkowski p. 7 Hogansburg Dam decommission and removal: Removal of first impassible barrier restores connection between St. Regis and St. Lawrence Watersheds A. David p. 9 Fort Plain Waterways: Stories of then and now in an Erie Canal town L. Elliott, C. Herron, G. Hoffman, W. MaGinnis, S. Paradiso, S. Rogers 10 The 2019 mid-winter ice jam event on the lower Mohawk River, New York J.I. Garver p. 11 Expansion of Invasive Round Goby in the Mohawk River-Barge Canal System S. D. George, B.P. Baldigo, C.B. Rees, M.L. Bartron p. 17 Nature-induced and human-instigated water deprivation sparks conflict in the Middle East A. Ghaly p. 18 Oroville Dam's main and emergency spillways: two near-miss disasters A. Ghaly p. 19 Identification of a point source for plastic pollution in upstate New York: a case study of Mayfield Lake K.N. Hemsley, L.G. English, C Cherizard, D.J. Carlson, J. McKeeby, S. Hadam, E. McHale p. 20 Stockade Resilience: Feasibility analysis of flood mitigation alternatives and design of mitigation measures to protect Schenectady’s Stockade Neighborhood M. Irwin p. 27 A four-year series of snap-shots: Data and observations from a Mohawk River water quality project as it enters Year Five of a longitudinal study N.A. Law, B.L. Brabetz, L.M. Wanits, L. Cao, S. Rogers, C. Rodak, J. Epstein, J. Lipscomb, D. Shapley p. 33 Aquatic invasive species in the Mohawk River Watershed: the devil is in the details C. McGlynn p. 34 United States Coast Guard Auxiliary: Recreational Boating Safety in the Mohawk Watershed D. Miller p. 35 The impact of alternative preservation methods and storage times on the δ13C of dissolved inorganic carbon in water M. Miller, L. Piccirillo, A. Verheyden, D. Gillian p 36 The importance of the West Canada Creek and FERC re-licensing for the WCC hydroelectric projects B. Nador p. 37 Overview of the Schoharie Creek Watershed flood mitigation study P. Nichols p. 41 Observations on dissolved and total metal concentrations in the Mohawk River in Utica and Rome, NY C. Rodak and N. Diers p. 42 Phosphorus monitoring prioritization in Mohawk River basin sub-watersheds using LENS M. Schnore, A.J. Smith, B. Duffy, K. Stainbrook, C. Stoll, Z. Smith p. 43 What's up with the Mohawk Delta? Insights from community water quality monitoring at the mouth of the river D. Shapley, J. Lipscomb, J. Epstein, S. Pillitteri, B. Brabetz, N.A. Law, A. Juhl, C. Knudson, G. O’Mullan, C. Rodak p. 45 Confirming the presence of microplastics in Capital Region fish using a novel no-kill abdomen massage A. Shimkus, J.A. Smith p. 48 Extreme rainfall, high water, and elevated microplastic concentration in the Hans Groot Kill: implications for the Mohawk River J.A. Smith, E. Caruso, N. Wright p. 53 Reconnecting waters for eels and river herring: towards resilience building approaches for dam removal action in the Hudson River watershed K. Smith, A.M. Feldpausch-Parker, K.E. Limburg p 59 Innovative approach to deliver a $300 million treatment plant upgrade for Oneida County, New York J. Story, R. Ganley, S Devan p. 60 Characterization of carbon export in Upstate New York: initial geochemical characterization of six rivers J. Wassik, J. Gehring, C. Horan, M. Stahl p. 65 Baseline monitoring of physical parameters and Enterococci levels in the Hans Groot Kill, Schenectady, NY E. Willard-Bauer, J.A. Smith, J.I. Garver p. 69
Conference Paper
Full-text available
A 27 km (17 mile) long ice jam formed during a January mid-winter breakup event, and it stayed in place for most of the winter. By historic standards this was the longest to have formed in decades, and thickness estimates were made to better understand the hazard and the nature of the ice in constriction points. Unmanned aerial system (UAS) photogrammetry and Structure from Motion (SfM) at two sites was done to better understand the structure and thickness of the ice. In the toe of the jam, in the Rexford Knolls, thickness is estimated to be between ~1.2 and 3.0 m (4-10 ft) thick for floating and thickened ice that meets sheet ice near Lock E7. At Lock E9, about 22 km (13.5 mi) up river, topographic mapping on the deflated and ground ice rubble reveals that the ice was between 1.8 and 2.7 m (6-9 ft), but ridges are as thick as 3.6 and 4.6 m (12-15 ft). UAV/UAS use is in its infancy in ice jam work, but imaging and mapping will be transformative in work aimed at assessing the hazard and understanding the science behind jams. The 2018 Jam ultimately broke up on 22 February, but only after causing backup flooding in the historic Stockade district in Schenectady.
Conference Paper
Full-text available
A 27 km (17 mile) long ice jam formed during a January mid-winter breakup event, and it stayed in place for most of the winter. By historic standards this was the longest to have formed in decades, and thickness estimates were made to better understand the hazard and the nature of the ice in constriction points. Unmanned aerial system (UAS) photogrammetry and Structure from Motion (SfM) at two sites was done to better understand the structure and thickness of the ice. In the toe of the jam, in the Rexford Knolls, thickness is estimated to be between ~1.2 and 3.0 m (4-10 ft) thick for floating and thickened ice that meets sheet ice near Lock E7. At Lock E9, about 22 km (13.5 mi) up river, topographic mapping on the deflated and ground ice rubble reveals that the ice was between 1.8 and 2.7 m (6-9 ft), but ridges are as thick as 3.6 and 4.6 m (12-15 ft). UAV/UAS use is in its infancy in ice jam work, but imaging and mapping will be transformative in work aimed at assessing the hazard and understanding the science behind jams. The 2018 Jam ultimately broke up on 22 February, but only after causing backup flooding in the historic Stockade district in Schenectady.
Conference Paper
Full-text available
Ice jams are an annual occurrence on the Mohawk River (NY). Historically, river breakup and potential jamming occurs in mid to late March, although a number of important mid-winter events have occurred in the last several decades (Garver and Cockburn, 2009). Ice jams are relatively common on northern rivers, but the lower Mohawk River is particularly vulnerable to ice jams because several key features that result in chronic problems in a 25 km stretch (~15 miles) between Lock 9 and Lock 7. The City of Schenectady is in the middle of this section of the river, and therefore the low-lying areas in the city face a significant and unique hazard that is challenging for Emergency Management. Three primary ingredients make this part of the river prone to ice jamming. First we can show that many ice-out events are linked to significant discharge from headwaters, especially from the Catskill-draining Schoharie Creek. This north-draining river can have significant discharge before other more northern parts of the watershed especially in weather systems with south-to-north warming and heavy precipitation that hugs the Atlantic Coast. Second, we know that much of the Mohawk River is relatively flat with a low gradient, and thus a large volume of sheet ice is produced in the winter, and this ice produces the largest and most durable blocks for the initiation of ice jams. Third, the lower section of the Mohawk River has an unusual set of constrictions on the flood plain, both natural and man-made. This latter point is important because although some aspects of the hazard can be remediated, there is a large natural constriction at the Rexford Knolls. The Knolls are marked by high bluffs, a deep channel, and no floodplain from the Rexford Bridge to near the Vischer Ferry Dam (Lock E7). This section of the river is relatively young having been captured forcing abandonment of the more northerly course (north up the current Alplaus channel) at about 10 ka. A number of artificial barriers and constrictions include bridges and abutments (both active and abandoned). Figure 1: Map of key features related to ice jamming on part of the lower Mohawk River (NY).
Conference Paper
Full-text available
Ice jams are an annual occurrence on the Mohawk River. As a northern temperate river, ice jams are expected, but it is clear from the occurrence and relative frequency of ice jams, that the Mohawk is particularly vulnerable to ice jams and the hazards associated with them. Here we briefly review the history of significant ice jams, we highlight research on reconstructing ice jams, and then we propose an active monitoring system that could be used by emergency personnel to better respond to active jams during breakup. Ice jams occur when the frozen river breaks up during events that result in rapid increase in discharge. Ice out and ice jams always occur on the rising limb of the hydrograph, when the floodwaters are building. When flow starts to rise it is not uncommon for unimpeded ice runs to develop, but invariably the ice gets blocked or impeded along the way by constrictions in the river, especially where the flood plain is reduced in size. In a survey of the past ice jamming episodes, we have come to the conclusion that any restriction or narrowing of the flood plain and constriction of the channel is a possible jam point (Johnston and Garver, 2001). An important point worth keeping in mind is that deep sections of rivers move more slowly than shallow ones, and therefore surface flow and therefore ice movement is reduced. So, a transition from a shallow to deep channel may generate a point where ice can backs may occur up, regardless of floodplain geometry.
Article
The breakup of the ice cover in cold-region rivers is a brief but seminal period of their hydrologic regime, with important ecological and socio-economic implications. The main driver of ice breakup processes is the flow discharge hydrograph. It is generated by runoff from snowmelt and rainfall but can be modified by rapid release of water from storage as the ice cover recedes by ablation and mechanical breaking up. Despite its potential importance, there is very limited quantitative information concerning the hydrodynamic processes that control storage release during ice breakup in rivers, while the issue of climate change underscores the need for improved understanding of the relevant mechanisms. Quantitative analysis for assumed prismatic channels shows that ablation and sustained ice dislodgment and breaking can cause significant flow enhancement via storage release. The latter process is far more dynamic than ablation and, under certain conditions, may lead to formation of a self-sustaining wave (SSW). Analytical results are applied to natural stream conditions, using the Lower Peace River as a case study. Observed rates of ice recession typically indicate ice melt as the dominant process. A rare occurrence of rapid ice breaking over hundreds of kilometres (2014) indicated partial agreement with the SSW concept and revealed that discrepancies may arise from the characteristic irregularity of rivers. Impacts on storage release by climate-driven changes to river ice regimes are examined, along with their implications to ice-jam formation and associated flooding.
Field measurements and analysis of waves generated by ice-jam releases
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Beltaos, S., 2005. Field measurements and analysis of waves generated by ice-jam releases. In Proceedings, 13th Workshop on the Hydraulics of Ice Covered Rivers, Hanover, NH (pp. 227-249).
Mapping and Volumetric calculations of the
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Marsellos, A.E., Garver, J.I., and Cockburn, J.M.H., 2010, Mapping and Volumetric calculations of the January 2010 Ice Jam Flood, Lower Mohawk River, using LiDAR and GIS;
Major Floods on the Mohawk River
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Scheller, M., Luey, K., and Garver, J.I., 2002. Major Floods on the Mohawk River (NY): 1832-2000. Retrieved March 2014 from http://minerva.union.edu/garverj/mohawk/170_yr.html
USGS Ice jam and flood monitoring
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Wall, G., Gazoorian, C. and Garver, J.I., 2013, March. USGS Ice jam and flood monitoring: Mohawk River, Schenectady, in Proceedings of the 2013 Mohawk Watershed Symposium, Union College, Schenectady, NY, p.83-85. Invited Presentation