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Dam Removal and Stream Restoration Improve Fislmnd Wildlife
Habitat in the East Branch of Wappinger Creek
Waterbody Improved
For more than 50 years, the Shapp Pond Dam near the outlet of
the East Branch of Wappinger Creek in Dutchess County, New
York, had blocked the passage of imperiled migratory fish such as American eel, disrupted natural
flow and sediment regimes, and created artificial lentic habitat that favored non-native and invasive
species. In 2016, the dam owner, the local soil and water conservation district, and the New York
State Department of Environmental Conservation's (NYSDEC's) Hudson River Estuary Program (HREP)
completed a cooperative project to remove the Shapp Pond Dam. Removal of the dam facilitated
streambank stabilization and riparian habitat recovery throughout the East Branch of Wappinger
Creek. After restoration, HREP and Cornell University documented significant improvements in
the physical habitat quality and macroinvertebrate community that will help the stream meet its
designated aquatic life and fishing use.
East Branch of Wappinger Creek
Problem
The East Branch of Wappinger Creek drains an area of
roughly 86 square kilometers and is a major tributary
to the Hudson River Estuary (Figure 1). Over the last
century, a suite of anthropogenic stressors, including
agricultural nonpoint source pollution, urbanization
and hydromodification contributed to water qual-
ity and aquatic habitat degradation. A number of
low-head dams throughout the watershed fragment
aquatic habitat and impair natural riverine functions
and ecological processes.
The 12-foot-hlgh Shapp Pond Dam blocked the
passage of Imperiled migratory fish such as American
eel, disrupted natural flow and sediment regimes, and
created artificial lentic habitat that favored non-native
and invasive species. The impoundment caused
streamflow stagnation that contributed to elevated
water temperatures, lower dissolved oxygen levels,
and a greater probability of harmful algai blooms. In
addition, given its poor structural condition, the dam
represented a flood and safety hazard for the dam
owner and downstream property owners.
in 2016, NYSDEC, in collaboration with the New
York State Water Resources Institute and Cornell
University, collected macroinvertebrate and substrate
samples and characterized the habitat quality within
Wappinger Creek
Figure 1. Wappinger Creek is in southeastern New York.
the impounded section of the river. These analyses
indicated that the stream macroinvertebrate com-
munity as well as the aquatic and riparian habitat were
negatively affected by the dam. Significant differences
in fish communities were found below and above the
dam. The warmer waters of the impoundment con-
tained silt that was suboptimal for cold water species
(e.g., trout) and species that prefer gravel substrate
(e.g., Longnose Dace,. Eastern Blacknose Dace). Fewer

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Figure 2. Project site before and after dam removal.
American eel were found above the dam than in the
downstream habitat as well. Dams are known to be sig-
nificant barriers to resident and migratory fish species
and contribute to habitat fragmentation and degrada-
tion, especially in high-quality cold-water tributaries.
Story Highlights
Using grant funds from the NYSDEC Hudson River
Estuary Program, the Dutchess County Soil and Water
Conservation District (SWCD) developed a restoration
plan that included removing the dam while retaining
some remnants of the dam and adding some ero-
sion control along the streambank near the home
for stabilization. The project partners implemented
the restoration project in the summer of 2016
(Figure 2). After removing the dam, the SWCD planted
native trees, shrubs and grasses along the formerly
impounded area to reestablish a vegetated corridor. To
document the ecological response and recovery of the
stream, the team monitored fish, macroinvertebrate
and substrate at locations both upstream and down-
stream of the dam.
Results
Restoration efforts restored connectivity to over five
miies of stream habitat. Bloassessment data collected
by the NYSDEC and Cornell University over the course
of three years show clear recovery of the degraded
upstream section of the river.
For instance, Biological Assessment Profile (BAP)
scores that characterize the integrity of the macroin-
vertebrate community show improvement within the
impounded section from "moderately impacted" to
"slightly impacted" after removal of the dam (Table 1).
Data suggests that the formerly impounded section of
the East Branch of the Wappinger Creek now sup-
ports aquatic life uses. Likewise, qualitative habitat
assessment scores obtained using the Stream Visual
Assessment method suggests an improvement in the
stream and riparian habitat in the impounded section
following dam removal (see Table 1). Worth noting is
the improvement in both metrics in the unimpounded
(downstream) section from pre- and post-removal, as
well. Moreover, particle size distribution within the
impounded section coarsened substantially post-
removal, indicating a mobilization of impoundment
sediments and a restoration of natural I otic benthic
habitat. (For more information on the BAP completed
in East Branch of Wappinger Creek, see https://www.
dec.ny.gov/docs/water_pdf/bapnarrativel8.pdf.)
Partners and Funding
Engineering, demolition and streambank stabiliza-
tion efforts were funded by the New York State
Environmental Protection Fund through an HREP grant
for Tributary Restoration and Resiliency, awarded
to the Dutchess County SWCD ($96,408). Biological
and physical habitat monitoring data were collected
by researchers from Cornell University with funding
support from the New York State Water Resources
Institute ($33,401). Riparian planting was supported by
HREP's Trees for Tribs Program.
Table 1. Pre- and post-removal assessment data.


Stream Visual
Assessment Score1
Biological Assessment
Profile Score2
Year
Removal
Status
Impounded
section
Unimpounded
downstream
section
Impounded
section
Unimpounded
downstream
section
2016
Pre-removal
6.2
7.0
3.5
7.4
2017
Post-removal
8.5
8.5
6.4
7.5
2018
Post-removal
8.7
8.8
6.3
7.5
1SVA scores: 1-2.9 = severely degraded, 3—4.9 = poor, 5-6.9 = good, 9-10 = excellent
2 BAP scores: <2.5 = severely impacted, 2.5-5 = moderately impacted, 5-7.5 = slightly
impacted, >7.5 = non-impacted
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-20-001D
January 2020
For additional information contact:
Don Tuxill
NYSDEC
518-402-8168
don.tuxill@dec.ny.gov

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