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Section 319
NONPOINT SOURCE PROGRAM SUCCESS STURY
Kfurde- Island
Removing Beaver Dams Reduces Phosphorus Impairment in the
Chickasheen Brook Watershed
Waterbody Improved .
Chickasheen Brook, Yawgoo Pond, and Barber Pond are
interconnected waterways in southern Rhode Island. Water quality
monitoring data collected between 1998 and 2002 showed elevated phosphorus concentrations
attributed to the inundation of Arrow Swamp, which flows into Chickasheen Brook, due to beaver
activity. As a result, the Rhode Island Department of Environmental Management (RIDEM) added the
three waterbodies to the state's Clean Water Act (CWA) section 303(d) list of impaired waters: Barber
Pond for low dissolved oxygen (DO) (1998), Yawgoo Pond for low DO (1998) and total phosphorus
(TP) (2002), and Chickasheen Brook for TP (2002). Removal of beavers and their dams restored the
fiow regime to Chickasheen Brook, reducing phosphorus levels in the brook and downstream ponds.
Monitoring results show reduced phosphorus levels, indicating that management efforts have made
significant progress toward meeting water quality standards.
Problem
Chickasheen Brook, Yawgoo Pond, and Barber Pond
are in southern Rhode Island within the towns of
Exeter and South Kingstown (Figure 1). The head-
waters of Chickasheen Brook originate in Maple
Swamp and flow approximately 1.6 miles, entering
Arrow Swamp just upstream of 143.4-acre Yawgoo
Pond. The brook flows for approximately 1,600 feet
from Yawgoo Pond to another wetland before
entering the approximately 28.5-acre Barber Pond.
Chickasheen Brook from its headwaters to Yawgoo
Pond is designated a Class A waterbody, suitable as
a source of public drinking water supply, for primary
and secondary contact recreation, and for fish and
wildlife habitat. The remainder of Chickasheen
Brook, Yawgoo Pond, and Barber Pond are designat-
ed as Class B waterbodies, suitable for primary and
secondary recreation and fish and wildlife habitat.
The surrounding watershed is predominately
undeveloped; approximately 48 percent of the
watershed is forested. Other land uses include
low- to medium-density residential development
(11 percent), agriculture (11 percent), and industrial/
commercial (3 percent). Trained volunteers from
the University of Rhode Island's Watershed Watch
program have monitored sites in the watershed
since 1988. By 1990, water quality deterioration was
documented in both ponds, with clarity declining
and chlorophyll (indicating algal growth) increasing to
hypereutrophic levels. Prompted by local complaints
Figure 1. The Chickasheen Brook watershed is in southern Rhode
Island.
and Watershed Watch data, RIDEM investigations
identified two shellfish processing facilities located
near Chickasheen Brook, between Maple and Arrow
Swamps, as causes of high phosphorus loadings to
the groundwater, brook, and downstream ponds.
Harbour Shellfish Site
Hillside Shellfish Site
Maple Swamp
Chickasheen
Brook
Sampling Site
Yawgoo Pond
Legend
Road
| | Pond
Wetland
Streams
I I Watershed Boundary
Upper Chickasheen Brook Watershed
Beaver Dam Removal Site / A™, Swamp
Sampling Site
Barber Pond

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RIDEM remediation, enforcement, and the closure of
the two facilities resulted in improved water quality
in the brook and ponds between 1991 and 1997.
Beginning in 1998, conditions in the brook and
ponds again worsened with a dramatic increase
in TP entering Yawgoo Pond from Chickasheen
Brook—causing algal blooms and a shift to
blue-green algae in the pond Data collected by
Watershed Watch between 1998 and 2002 showed
that at the points where it enters Yawgoo and
Barber Ponds, Chickasheen Brook consistently
exceeded Rhode Island's TP criterion of 25 micro-
grams per iiter (/jg/L) and had excess algal growth.
Yawgoo Pond consistently failed Class B standards
for DO, total phosphorus, and also had excess
algal growth. Barber Pond also failed to meet
the DO standard. Based on these data, RiDEM
added the three waterbodies to the state's list of
impaired waters: Barber Pond for low DO (1998),
Yawgoo Pond for low DO (1998) and TP (2002), and
Chickasheen Brook for TP (2002).
Results
Project Highlights
In response to the increasing phosphorus con-
centrations in Yawgoo Pond, Watershed Watch
conducted a survey of the watershed in the sum-
mer of 2001. Surveyors identified a sizable beaver
dam flooding Arrow Swamp, the principal receiving
waterbody of the former shellfish processing plants,
upstream from Chickasheen Brook (Figure 2).
RIDEM developed a TP total maximum daily load
(TMDL) for the three waterbodies in 2004. The
TMDL attributed high phosphorus levels to beaver
dams in the waters of Arrow Swamp, which led
to the suspension of phosphorus-enriched sedi-
ment from historic phosphorus loadings from the
shellfish processing facilities. As a result, when
the swamp flooded and spilled out of the dam, the
phosphorus-enriched water traveled downstream to
Chickasheen Brook, Yawgoo Pond, and Barber Pond.
The Arrow Swamp beaver dam was removed in the
fall of 2001 and the property owner committed to
maintaining the breach of this dam. The beavers
built another dam downstream, which did not cause
flooding of Arrow Swamp and has since been aban-
doned. Removal of the beaver dam has returned
Arrow Swamp to its previous regime of periodic
flooding and draining, avoiding conditions that led
to phosphorus impairment.
Figure 2. An algal bloom is visible
behind a beaver dam constructed at
the outlet of Arrow Swamp.
Since the beaver dam
removal, phosphorus
concentrations in
Chickasheen Brook
have decreased
dramatically. Average
annual phosphorus
concentrations
decreased from
more than 200 /jg/L
(1998-2002) to 22jjg/L
(2006-2010). At the
sampling location just
upstream of Yawgoo
Pond, Chickasheen
Brook now meets
RIDEM's water quality
criterion for phospho-
rus. As a result, aver-
age annual phosphorus
concentrations at the
surface of Yawgoo
Pond decreased
from 35 /jg/L (2001)
to 15-20 /jg/L
(2006-2010). Phosphorus concentrations at the
pond bottom remain elevated due to a high internal
phosphorus and nitrogen load, which could be
addressed through alum treatments. Watershed
Watch continues to monitor Chickasheen Brook,
Yawgoo Pond (Figure 3), and Barber Pond.
Figure 3. Phosphorus levels in Yawgoo
Pond have declined.
Partners and Funding
Watershed Watch is led by the University of Rhode
Island's (URI) Department of Natural Resource
Sciences and URI Cooperative Extension through
collaboration with URI Coastal Fellows, URI College
of the Environmental and Life Sciences, RIDEM,
the Wood-Pawcatuck Watershed Association, local
sponsors, and the federal government. The program
is aimed at providing training and equipment to
volunteer "citizen scientists" who conduct multi-
year surface water quality monitoring according to
strict quality assurance procedures. For more than
two decades, Watershed Watch has used CWA sec-
tion 319 funds undera contract with RIDEM RIDEM
currently provides approximately $50,000 annually
in CWA section 319 funds to support the Watershed
Watch program.
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 84.1-F-14-Q0TW
August 2014
For additional information oontact:
Betsy Dake
Rl Department of Environmental Management
401-222-4700, extension 7230
Betsy, Da ke@dem.ri.gov

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