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National Assessment Database

Assessment Data for
Connecticut, Thames Watershed (8 Digit USGS Cataloging Unit), Year 2006

Description of this table
For a report glossary please click here.

Click on the Water Name link to get 305(b) Lists/Assessment Unit Information Report

Table Legend: Water Status is GoodWater Status is Threatened Water Status is ImpairedWater Status has not been Assessed

Water Name Assessment Unit ID Location Map State Water Type Water Size Unit Water Status
Alewife Cove-01 CT2004-E_01 Alewife Cove, Waterford. Map Assessed Water CT ESTUARY .06 SQUARE MILES IMPAIRED
Amos Lake (Preston) CT3002-02-1-L2_01 East of Rte 164, Preston. Map Assessed Water CT FRESHWATER LAKE 112.42 ACRES IMPAIRED
Avery Pond (Preston) CT3002-04-1-L1_01 East of Rte 164, north of Rte 2, Preston. Map Assessed Water CT FRESHWATER LAKE 45.62 ACRES GOOD
Bentley Brook-01 CT3900-09_01 From mouth at confluence with Yantic River (just DS of Route 2 crossing, on Bozrah/Norwich town border), US to headwaters, Gager Road, Bozrah. Map Assessed Water CT RIVER 2.24 MILES GOOD
Bride Brook Estuary-01 CT2206-E_01 Bride Brook estuary from north side of railroad crossing north to Rt. 156, East Lyme. Map Assessed Water CT ESTUARY .03 SQUARE MILES IMPAIRED
Bride Brook-01 CT2206-00_01 From head of estuary (salt water limit, just DS of Route 156 crossing), US to Bride Lake outlet dam (just US of North Bride Brook Road), East Lyme. Map Assessed Water CT RIVER .7 MILES IMPAIRED
Bride Brook-02 CT2206-00_02 From inlet to Bride Lake (northwest portion, just DS of North Bride Brook Road crossing), US to headwaters (marsh on south side of Route 1), East Lyme. Map Assessed Water CT RIVER 2.13 MILES IMPAIRED
Copps Brook-01 CT2102-00_01 From mouth at Quiambog Cove (parallel to Cove Road), US to Palmer (Mystic) Reservoir outlet dam (just US of Jerry Brown Road crossing), Stonington. Map Assessed Water CT RIVER .77 MILES IMPAIRED
Copps Brook-02 CT2102-00_02 From inlet to Palmer (Deans/Mystic) Reservoir (just DS of Pequot Trail (Route 234) road crossing), Stonington, US to headwaters (just US of Mystic Road (Route 201) crossing, North Stonington. Map Assessed Water CT RIVER 4.32 MILES GOOD
Dodge Pond (East Lyme) CT2205-02-1-L1_01 East Lyme; near Niantic village center, east of Rte 161, north of Rte 156. Map Assessed Water CT FRESHWATER LAKE 29.59 ACRES IMPAIRED
Fenger Brook-01 CT2000-30_01 From mouth at head of tide, Alewife Cove (just DS of Niles Hill Road (Route 213) crossing), US to headwaters (southeast of Clark Lane and Chester Street intersection), Waterford. Map Assessed Water CT RIVER 3.47 MILES IMPAIRED
Fitchville Pond (Bozrah) CT3900-00-4-L1_01 Split by Rte 2 in Bozrah, impoundment of Yantic River. Map Assessed Water CT FRESHWATER LAKE 58.54 ACRES GOOD
Flat Brook (Ledyard)-01 CT3000-08_01 From mouth at confluence with Thames River (inlet to Long Cove, North of Navy Base) Gales Ferry/Ledyard, US to headwaters at unnamed pond, Groton (Brook runs North). Map Assessed Water CT RIVER 1.09 MILES GOOD
Gardner Brook-01 CT3906-00_01 From mouth at confluence with Yantic River (inlet to Fitchville Pond, southeast side parallell to Route 163), US to Gardner Lake outlet dam (just US of Lake Road crossing), Bozrah. Map Assessed Water CT RIVER 4.84 MILES GOOD
Gardner Lake (Salem/Montville/Bozrah) CT3906-00-1-L1_01 At junction of Salem, Montville and Bozrah. Map Assessed Water CT FRESHWATER LAKE 527.29 ACRES GOOD
Gorton Pond (East Lyme) CT2205-00-1-L3_01 East Lyme. Impoundment of Pataganset River. Map Assessed Water CT FRESHWATER LAKE 52.41 ACRES GOOD
Goshen Cove-01 CT2005-E_01 West of Goshen Point, Waterford, inland cove adjacent to Harkness Memorial State Park. Map Assessed Water CT ESTUARY .04 SQUARE MILES GOOD
Inner Quiambaug Cove-02 CT2102-E_02 SB/SA water, Quiambaug Cove area north of Amtrak crossing. Map Assessed Water CT ESTUARY .11 SQUARE MILES IMPAIRED
Jordan Cove-01 CT2201-E_01 Cove and tidal waters of Jordan cove and Pleasure Beach north of a line transect from Millstone Point on the west to White point on the east, Waterford. Map Assessed Water CT ESTUARY .77 SQUARE MILES IMPAIRED
Kahn Brook-01 CT3900-07_01 From mouth at confluence with Yantic River (just DS of Fitchville Road crossing), US to chicken farm road crossing, Bozrah. Map Assessed Water CT RIVER .61 MILES IMPAIRED
Lake Of Isles (North Stonington) CT3002-06-1-L1_01 Near western border of North Stonington, north of Rte 2. Map Assessed Water CT FRESHWATER LAKE 91.25 ACRES GOOD
Lantern Hill Pond (Ledyard/North Stonington) CT2104-00-1-L1_01 Border of Ledyard and North Stonington; now part of Mashentucket Reservation. Map Assessed Water CT FRESHWATER LAKE 20.06 ACRES GOOD
Latimer Brook-01 CT2202-00_01 From mouth at confluence with Niantic River (head of tide at Banning Cove inlet, just DS of Route 1 crossing, south side of I95, east of exit 75), US to confluence with Cranberry Meadow Brook (parallel with Route 161), East Lyme Map Assessed Water CT RIVER 4.23 MILES GOOD
Latimer Brook-02 CT2202-00_02 From confluence with Cranberry Meadow Brook (parallel with Route 161), East Lyme, US to Beckwith Pond outlet dam (boundary of drinking water watershed, just US of Route 85 crossing), Montville. Map Assessed Water CT RIVER 3.43 MILES GOOD
Latimer Brook-03 CT2202-00_03 From Beckwith Pond inlet (in marsh on northern side), US to headwaters at Barnes Reservoir outlet dam, Montville/Salem. Map Assessed Water CT RIVER 1.26 MILES GOOD
Long Island Sound East (Old Lyme Shore)-03 CT2006-E_03 Nearshore Old Lyme, from outlet of Mile Creek at west, east to Hatchett Point, Soundview Beach to Old Lyme Shores Beach coastline. Map Assessed Water CT ESTUARY .26 SQUARE MILES IMPAIRED
Long Pond (Ledyard/North Stonington) CT2104-00-1-L2_01 Ledyard, North Stonington border. Map Assessed Water CT FRESHWATER LAKE 111.31 ACRES GOOD
Mumford Cove-01 CT2003-E_01 Inner, tidal portion of Mumford Cove, above a line drawn from Mumford point on the west, and Groton Long Point on the east, at the point just below Venetian Harbor. Includes Venetian Harbor. All SA water. Map Assessed Water CT ESTUARY .51 SQUARE MILES IMPAIRED
Mystic River Estuary-01 CT2106-E_01 Offshore area from west at Morgan Point, Noank east through Mason Point, to Enders Island, on the eastern tip of Mason's Island, out to the CT-NY state line. Map Assessed Water CT ESTUARY 1.99 SQUARE MILES GOOD
Mystic River Estuary-02 CT2106-E_02 All SB tidal waters of the Mystic River Estuary from west at Morgan Point, Noank east to western side of Mason Island, and north to head of tide near Route 27. Map Assessed Water CT ESTUARY 1.41 SQUARE MILES GOOD
Niantic Bay And Offshore-03 CT2204-E_03 Niantic Bay and offshore from west at Black Point, northeast to Millstone point, north to Sandy Point area, EXCLUDING 0.38 sq mi near southwesr shore of Niantic Bay from Pond Point north to RR tracks (segment-01), Niantic. Map Assessed Water CT ESTUARY 3.78 SQUARE MILES IMPAIRED
Offshore Quiambaug Cove-01 CT2102-E_01 Offshore waters on west from the tip of Masons Island (Enders Island), east through Dodges Island, Andrews Island, and Lords Point to Wamphassuc Point, Stonington, out to CT-NY state line and excluding coves and inlets. Map Assessed Water CT ESTUARY 3.34 SQUARE MILES GOOD
Offshore from West Cove-01 CT2002-E_01 Water offshore from West and Palmer Coves, from the West at Groton Long Point, East to and around Mouse Island, ending at Morgan Point, Noank, and out to the CT state line. Shellfishing approved, class SA water. Map Assessed Water CT ESTUARY .82 SQUARE MILES GOOD
Oxoboxo Brook-01 CT3004-00_01 From mouth at head of tide (inlet to Gay Cemetery Pond, Horton Cove, Thames River), US to Wheeler Pond outlet dam, Montville. (Segment includes Rockland Pond) Map Assessed Water CT RIVER 2.62 MILES GOOD
Oxoboxo Brook-02 CT3004-00_02 From inlet to Wheeler Pond (northwestern portion, DS of Meeting House Lane road crossing), US to Oxoboxo Lake outlet dam. (Includes Scholfield Pond) Map Assessed Water CT RIVER 2.95 MILES GOOD
Pataganset Lake (East Lyme) CT2205-00-1-L2_01 East Lyme, Pataganset River system. Map Assessed Water CT FRESHWATER LAKE 125.7 ACRES GOOD
Pattagansett And Fourmile River And Coast-02 CT2206-E_02 Pattagansett River and Fourmile River estuaries; from Hatchett Point on west to Black Point on east, north to head of each estuary near Rte 156 crossing. Map Assessed Water CT ESTUARY 2.34 SQUARE MILES IMPAIRED
Pattagansett River-01 CT2205-00_01 From head of tide, just DS of Route 156 crossing, US to Gorton Pond outlet dam (just US of Roxbury Road crossing, east of Route 161 intersection), East Lyme. Map Assessed Water CT RIVER 1.2 MILES GOOD
Pattagansett River-02 CT2205-00_02 From inlet to Gorton Pond (northern side in marsh, just DS of I95 crossing), US to Pattagansett Lake outlet dam (just US of Route 1 crossing), East Lyme. Map Assessed Water CT RIVER 1.9 MILES GOOD
Pattagansett River-03 CT2205-00_03 From inlet to Pattagansett Lake (northwest portion of lake), US to Powers Lake outlet dam (just US of Upper Pattagansett Road crossing), East Lyme. Map Assessed Water CT RIVER .95 MILES GOOD
Pease Brook-01 CT3905-00_01 From mouth at confluence with Yantic River, Bozrah, US to headwaters (just US of Burnham Road crossing, Lebanon Map Assessed Water CT RIVER 9.63 MILES GOOD
Poquetanuck and Hewitt Brooks-01 CT3003-00_01 From mouth of Poquetanuck Brook (at confluence with Thames River, inlet to Poquetanuck Cove, just DS of Poquetanuck Road (Route 2A) crossing), US to confluence with Hewitt Brook, then CONTINUES US in Hewitt Brook to Hallville Pond outlet dam. Map Assessed Water CT RIVER 1.69 MILES GOOD
Powers Lake (East Lyme) CT2205-00-1-L1_01 East Lyme, Headwaters of Pataganset River. Map Assessed Water CT FRESHWATER LAKE 146.5 ACRES GOOD
Red Cedar Lake (Lebanon) CT3900-01-1-L1_01 South corner of Lebanon. Map Assessed Water CT FRESHWATER LAKE 132.92 ACRES GOOD
Seth Williams Brook-01 CT2103-00_01 From mouth at Whitford Brook on Ledyard/Stonington town line, US to Shewville Road crossing, Ledyard. Map Assessed Water CT RIVER .42 MILES GOOD
Seth Williams Brook-02 CT2103-00_02 From Shewville Road crossong, US to Highlands POTW (DS of Town Farm Road, parallel to Shewville Road), Ledyard. Map Assessed Water CT RIVER .53 MILES GOOD
Seth Williams Brook-03 CT2103-00_03 From Highlands POTW (DS of Town Farm Road crossing, parallel to Shewville Road), US to headwaters (US of Shewville Road crossing, south of Route 214 intersection), Ledyard. Map Assessed Water CT RIVER 2.1 MILES GOOD
Sherman Brook-01 CT3903-00_01 From mouth at confluence with Deep River, above Yantic River, Lebanon, US to headwaters (just US of Lebanon Avenue (Route 16 crossing), Colchester. (Segment includes Sherman Pond). Map Assessed Water CT RIVER 5.01 MILES GOOD
Spaulding Pond (Norwich) CT3800-00-6+L3_01 Mohegan Park, Norwich (Mohegan Park Rd) No Mapping Data CT FRESHWATER LAKE 14.3 ACRES IMPAIRED
Stonington Harbor-01 CT2001-E_01 SB waters of harbor south of Amtrak. Map Assessed Water CT ESTUARY .64 SQUARE MILES GOOD
Stonington Harbor-02 CT2001-E_02 0.34 sq mi of SB/SA waters north of Amtrak line, closed to direct harvest. Map Assessed Water CT ESTUARY .34 SQUARE MILES IMPAIRED
Susquetonscut Brook-01 CT3907-00_01 From mouth at confluence with Yantic River, bozrah/Norwich town border (just DS of RailRoad crossing), US to headwaters (just US of Bender Road crossing, along south side of Beaumont Highway and Rafferty Road intersection, Lebanon. Map Assessed Water CT RIVER 13.55 MILES GOOD
Thames River Estuary-01 CT3000-E_01 Mouth of Thames River and offshore SB waters, and north from I95 crossing to Stoddard Hill State Park, EXCLUDING Horton Cove, New London Harbor south of I95 to mouth, and all prohibited shellfishing areas other than administrative closures. Map Assessed Water CT ESTUARY 9.65 SQUARE MILES IMPAIRED
Thames River Estuary-02 CT3000-E_02 Shellfish prohibited Area from mouth of New London Harbor north to I95 crossing (Gold Star Bridge); and discontinuous coves where shellfishing is prohbited upto Stoddard Hill State Park (Horton, Smith, Mill, and Clark Coves), where segment-03 begins. Map Assessed Water CT ESTUARY 2.13 SQUARE MILES IMPAIRED
Thames River Estuary-03 CT3000-E_03 Upper Thames River Estuary from just south of Poquetanuck Cove, north to salt water limit in Norwich Harbor area (includes Shetucket River US to Greenville dam, and Yantic River US to Falls Mill lower dam). Includes both Poquetanuck and Trading Coves. Map Assessed Water CT ESTUARY 1.54 SQUARE MILES IMPAIRED
Trading Cove Brook-01 CT3001-00_01 From head of tide at confluence with Thames River (inlet to Trading Cove, just DS from Route 32 crossing), Norwich/Montville town line, US to headwaters (in marsh just US of Bozrah Road (Route 163) crossing), Montville. Map Assessed Water CT RIVER 7.24 MILES GOOD
Wequetequock Cove-01 CT2101-E_01 SB/SA water. Wequetequock Cove, from west at Stonington Point, east to Pawcatuck Point, out to CT-RI state line (Including Little Narragansett Bay). Map Assessed Water CT ESTUARY 1.97 SQUARE MILES IMPAIRED
Whitford Brook-01 CT2104-00_01 From mouth at head of Mystic River Estuary (at confluence with Haleys Brook, above Mystic River, DS of Route 27 crossing), Stonington/Groton town line, US to area east of the Shewville Road and Gallup Hill Road intersection, Ledyard/Stonington town line. Map Assessed Water CT RIVER 1.63 MILES GOOD
Whitford Brook-03 CT2104-00_03 From confluence with Seth Williams Brook, US to Whitford Pond outlet dam (just US of Whitford Road crossing), Ledyard/Stonington town line. Map Assessed Water CT RIVER .3 MILES GOOD
Whitford Brook-04 CT2104-00_04 From inlet to Whitford Pond (northeast portion of pond), Ledyard/Stonington town line, US to Long Pond outlet dam (just US of Lantern Hill Road crossing), Ledyard. Map Assessed Water CT RIVER .89 MILES GOOD
Yantic River-01 CT3900-00_01 From Vermont RailRoad crossing (just US of Falls Mill lower dam), Norwich, US to Fitchville Pond outlet dam (just US of Fitchville Road crossing), Bozrah. Map Assessed Water CT RIVER 6.46 MILES GOOD
Yantic River-02 CT3900-00_02 From Fitchville Pond inlet (Haughton Road crossing, north side of Route 2, exit 23), Bozrah, US to headwaters at confluence of Sherman Brook and Deep River, Lebanon. Map Assessed Water CT RIVER 5.93 MILES GOOD

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State Causes of Impairment

Connecticut, Thames Watershed

Description of this table
State Cause Name Size of Assessed Waters with Listed Causes of Impairment
Rivers, Streams, Creeks (Miles) Lakes, Ponds, Reservoir (Acres) Bays, Estuaries (Square Miles) Coastal Shorelines (Miles) Oceans, Near Coastal Waters (Square Miles) Wetlands (Acres) Great Lakes Shoreline (Miles) Great Lakes Open Waters (Square Miles) Inland Lake Shoreline (Miles) Great Lakes Connecting Channel (Miles)
CAUSE UNKNOWN 11.10 .00 7.56 .00 .00 .00 .00 .00 .00 .00
EXCESS ALGAL GROWTH .00 337.26 .00 .00 .00 .00 .00 .00 .00 .00
ESTUARINE BIOASSESSMENTS .00 .00 22.38 .00 .00 .00 .00 .00 .00 .00
NUTRIENT/EUTROPHICATION BIOLOGICAL INDICATORS .00 337.26 4.80 .00 .00 .00 .00 .00 .00 .00
LEAD 6.39 .00 .00 .00 .00 .00 .00 .00 .00 .00
MERCURY .00 88.77 .00 .00 .00 .00 .00 .00 .00 .00
ENTEROCOCCUS 9.56 .00 7.40 .00 .00 .00 .00 .00 .00 .00
CHLOROPHYLL-A .00 337.26 .00 .00 .00 .00 .00 .00 .00 .00
OTHER FLOW REGIME ALTERATIONS 1.54 .00 .00 .00 .00 .00 .00 .00 .00 .00
ESCHERICHIA COLI .00 28.60 .00 .00 .00 .00 .00 .00 .00 .00
OXYGEN, DISSOLVED .00 .00 22.50 .00 .00 .00 .00 .00 .00 .00
FECAL COLIFORM .00 .00 27.68 .00 .00 .00 .00 .00 .00 .00
DISSOLVED OXYGEN SATURATION .00 .00 22.50 .00 .00 .00 .00 .00 .00 .00

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Probable Sources Contributing to Impairment

Connecticut, Thames Watershed

 Description of this table
State Source Name Size of Assessed Waters with Probable Sources of Impairment
Rivers, Streams, Creeks (Miles) Lakes, Ponds, Reservoir (Acres) Bays, Estuaries (Square Miles) Coastal Shorelines (Miles) Oceans, Near Coastal Waters (Square Miles) Wetlands (Acres) Great Lakes Shoreline (Miles) Great Lakes Open Waters (Square Miles) Inland Lake Shoreline (Miles) Great Lakes Connecting Channel (Miles)
SANITARY SEWER OVERFLOWS (COLLECTION SYSTEM FAILURES) .00 .00 2.13 .00 .00 .00 .00 .00 .00 .00
CONTAMINATED SEDIMENTS .00 29.59 .00 .00 .00 .00 .00 .00 .00 .00
ON-SITE TREATMENT SYSTEMS (SEPTIC SYSTEMS AND SIMILAR DECENCENTRALIZED SYSTEMS) .00 112.42 10.33 .00 .00 .00 .00 .00 .00 .00
NON-POINT SOURCE 2.13 .00 6.33 .00 .00 .00 .00 .00 .00 .00
RESIDENTIAL DISTRICTS .00 .00 23.46 .00 .00 .00 .00 .00 .00 .00
OTHER SPILL RELATED IMPACTS .00 29.59 .00 .00 .00 .00 .00 .00 .00 .00
UPSTREAM IMPOUNDMENTS (E.G., PL-566 NRCS STRUCTURES) .77 .00 .00 .00 .00 .00 .00 .00 .00 .00
IMPACTS FROM HYDROSTRUCTURE FLOW REGULATION/MODIFICATION .70 .00 .00 .00 .00 .00 .00 .00 .00 .00
BASEFLOW DEPLETION FROM GROUNDWATER WITHDRAWALS .70 .00 .00 .00 .00 .00 .00 .00 .00 .00
UNSPECIFIED URBAN STORMWATER 3.47 .00 23.20 .00 .00 .00 .00 .00 .00 .00
ANIMAL FEEDING OPERATIONS (NPS) .61 .00 .00 .00 .00 .00 .00 .00 .00 .00
AGRICULTURE .61 .00 1.54 .00 .00 .00 .00 .00 .00 .00
FLOW ALTERATIONS FROM WATER DIVERSIONS .77 .00 .00 .00 .00 .00 .00 .00 .00 .00
COMBINED SEWER OVERFLOWS .00 .00 1.54 .00 .00 .00 .00 .00 .00 .00
MARINA/BOATING SANITARY ON-VESSEL DISCHARGES .00 .00 13.75 .00 .00 .00 .00 .00 .00 .00
MUNICIPAL POINT SOURCE DISCHARGES .00 .00 11.19 .00 .00 .00 .00 .00 .00 .00
SOURCE UNKNOWN 4.78 112.42 5.35 .00 .00 .00 .00 .00 .00 .00
ATMOSPHERIC DEPOSITION - NITROGEN .00 .00 1.54 .00 .00 .00 .00 .00 .00 .00
WATERFOWL .70 126.72 13.84 .00 .00 .00 .00 .00 .00 .00
INDUSTRIAL POINT SOURCE DISCHARGE .00 .00 2.13 .00 .00 .00 .00 .00 .00 .00

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Clicking anywhere on this watershed map will take you to the Enviromapper for Water website, where you can view and map various types of environmental information for the watershed. This information includes Superfund sites, water discharge permits, toxic releases, and more.

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