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NONPOINT SOURCE SUCCESS STURY
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Installing Infiltrating Catch Basins Helps Reduce Bacteria in
Greenwich Cove
Waterbody Improvsd Greenwich Cove is an important recreational arid boating area
in Greenwich Bay, an estuary that connects with the upper West
Passage of Narragansett Bay in Rhode Island, Greenwich Cove was added to the 2002 Clean Water
Act (CWA) section 303(d) list as impaired for swimming and boating recreation due to pathogens
(using fecal coliform as the indicator organism), Installing best management practices (BMPs) and
fixing failed septic systems reduced bacteria in the cove. Data (2012-2016) show that the cove
now meets water quality standards (WQS) under both dry and wet weather conditions, As a result,
Rhode Island Department of Environmental Management (RIDEM) has submitted Greenwich Cove
for removal from the 2016 list of impaired waters.
Problem
Greenwich Cove is bordered on the west by the town
of East Greenwich and on the east by Potowomut Point
in the city of Warwick (Figure 1). The Maskerchugg
River, the second largest freshwater tributary to
Greenwich Bay discharges to the head of Greenwich
Cove at its southern end. With a surface area of
1,1 square kilometers (km2) and a total watershed area
of 17.7 km2, Greenwich Cove offers mooring and dock-
ing space for boats along the East Greenwich shoreline
and supports a variety of land uses throughout its
watershed, including a forested state park, a golf
course, state highways, commercial properties, and
low- to high-density residential development.
Greenwich Cove was added to the 2002 CWA sec-
tion 303(d) list as impaired for swimming and boating
recreation due to pathogens (using fecal coliform
as the Indicator organism). In February 2006 the
U.S. Environmental Protection Agency (EPA) approved
a totai maximum daily load (TMDL) (dated December
2005) for Greenwich Cove as a part of the Greenwich
Bay Pathogen/Bacteria TMDL. This TMDL identified
the sources of impairment as direct stormwater dis-
charges, substandard and failing septic systems, water-
fowl, and wiidiife and domestic pet waste. Enterococci
were adopted as the recreational/swimming WQS
per the Beach Act (2000). The WQS requires that the
enterococci bacteria annual geometric mean must be
less than 35 colonies/100 milliliters (col/100 mL) of
water (samples collected between May and October).
Figure 1. Greenwich Cove is in eastern Rhode Island.
Project Highlights
Improvements in water quality conditions in
Greenwich Cove can be attributed to several actions
in the watershed that have occurred since the TMDL
was written, including the installation of BMPs to
improve water quality from stormwater runoff and
improvements to wastewater infrastructure. One of
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the largest BMPs installed was the result of the town
of East Greenwich's work under multiple grant projects
funded through several CWA section 319 grants. The
section 319 grants enabled East Greenwich to perform
a feasibility study to determine the best locations for
installing 10 infiltrating catch basins. Initially the town
had anticipated the need for only 10 of these catch
basins, but its studies found an additional 13 appro-
priate sites for catch basin construction. In 2012 the
town installed a total of 23 infiltrating catch basins in
the Greenwich Cove watershed. By capturing the first
flush of stormwater and allowing it to infiltrate into the
surrounding soils, East Greenwich was able to signifi-
cantly reduce its nonpoint source pollutant loadings to
Greenwich Cove.
East Greenwich also cleans the catch basins annually
together with frequent street sweeping throughout
the watershed, and has replaced a sewer main along
Water Street, which runs adjacent and parallel to
Greenwich Cove. While there was no evidence that the
sewer main was exfiltrating sewage, it was known to
be affected by infiltration. RIDEM's Shellfish Program
identified two storm drains with elevated bacterial
and coliphage levels discharging into Greenwich Cove
during a periodic shoreline survey in 2005. Working
with East Greenwich and Warwick, RIDEM's Office of
Compliance and Inspection conducted illicit discharge
detection studies of the two storm drain networks.
The studies found several illicit connections from
failing septic systems, including one at a senior living
facility as well as a mill property. Both of these sources
were connected to sewers as a result of the studies.
Investigations also resulted in identification of a marina
with a cesspool which subsequently was connected to
a sewer line and the correction of an illicit gray water
discharge that had been entering the storm drain
network.
In addition, in the neighboring city of Warwick, a CWA
section 319 grant was used to connect the drasti-
cally failing septic system of a fire station (Fire Station
#5) to the Warwick sewers. The system had failed to
the point that septage was backing up into the fire
station, putting fire personnel health at risk, as well as
contributing raw septage to the Maskerchugg River
during rain events. The closure of this septic system
and the connection of Fire Station #5 to the sewer line
eliminated a source of pathogens to the Maskerchugg
River, which flows into Greenwich Cove.
Table 1. Annual enterococci geometric mean data
show that Greenwich Cove (at the East Greenwich
town dock) meets the applicable WQS1.

2012
2013
2014
2015
2016
Number of Samples
6
6
6
6
6
Enterococci
(col/100 mL)
27.9
13.6
22.2
14.2
9.9
1WQS for enterococci = annual geometric mean of no more than
35 colonies/100 milliliters of water, collected monthly from May to
October.
Results
In the 2005 TMDL, RIDEM used fecal coliform data
from 2001 and 2002 to characterize the water quality
condition in Greenwich Cove. At that time, data col-
lected under wet weather conditions did not meet the
Rhode Island recreational WQS for fecal coliform bac-
teria. In recent years, the area has been sampled by
volunteers from Watershed Watch for enterococci, the
current Rhode Island recreational indicator bacteria.
These recent data (2012-2016) show that Greenwich
Cove is meeting the applicable Rhode Island WQS for
enterococci under both dry and wet weather condi-
tions (Table 1). In addition, Greenwich Cove is sampled
by the RIDEM Office of Water Resources Shellfish
Program for fecal coliform under dry weather condi-
tions and has met the fecal standard during the same
time period. As a result of these improvements, RIDEM
proposes to remove the Greenwich Cove bacteria
impairment from the state's 2016 list of impaired
waters for swimming and boating recreation, subject
to EPA approval.
Partners and Funding
Partners included the University of Rhode Island
Watershed Watch (monitored water quality); the town
of East Greenwich, Rhode Island (provided match-
ing funds for nonpoint source projects); the RIDEM
Shellfish Program (conducted effort to detect illicit
discharges into storm drains); and the city of Warwick,
Rhode Island (provided matching funds for the connec-
tion of Fire Station #5 to the municipal sewer system).
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PRO^°
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-18-001D
January 2018
For additional information contact:
Betsy Dake
Rhode Island Department of Environmental
Management
401-222-4700 • Betsy.Dake@dem.ri.gov

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