Thames River Basin Partnership
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Thames River Watershed and TMDLs

The Thames River Basin is a 1,478-square mile drainage area located primarily in eastern Connecticut, with upstream drainage areas in south-central Massachusetts and western Rhode Island. (Thames Science Plan, USGS)  Neatly outlined in the USGS Thames Science Plan, the provisions of the Clean Water Act (CWA) require each state to monitor, assess, and report on the quality of its waters. In Connecticut, the Department of Environmental Protection is required to:

A Total Maximum Daily Load (TMDL) specifies the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and allocates pollutant loadings among point and nonpoint pollutant sources. By law, EPA must approve or disapprove lists and TMDLs established by states, territories, and authorized tribes. The US EPA issued regulations in 1985 and 1992 that implement the section 303(d) of the Clean Water Act - the TMDL provisions.

The Clean Water Act (CWA) is the cornerstone of surface water quality protection in the U.S.  It is also one of the nation’s most successful environmental laws.  The statute has prevented billions of pounds of pollution from spilling into our nations waterways.  In 1972, only 36% of the country’s lakes and rivers were safe for swimming.  After thirty years, more than 66% of waters are safe enough for fishing and swimming.  However, water pollution remains a serious threat.

The CWA requires a variety of measures to reduce polluted discharges, finance municipal wastewater treatment facilities, and manage runoff.  These controls are designed for "the protection and propagation of fish, shellfish, and wildlife and recreation in and on the water.”  In more simple terms, it establishes criteria for whether water is considered ‘fishable’ or ‘swimmable.’  If water is found to not meet criteria as fishable and swimmable, then it is listed as impaired for that designated use.  It is the responsibility of each State to monitor their rivers and streams and produce a biannual report on the State’s water quality to the US Congress.  Click on report to view Connecticut’s most recent assessment.

TMDLs that have been developed for the greater Thames River watershed include the upper Willimantic River in Stafford, Eagleville Brook in Mansfield and for all of Long Island Sound into which the Thames River discharges. 

Other great web resources for TMDL information include the Virginia Tech Center for Watershed Studies, and Maryland, Maine and New Hampshire each host websites with useful information.


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