Willimantic River Water Quality
Water Quality Classifications
The 2010 report includes three types of designated uses as being fully supported, not supported or unknown (untested). The river and tributaries are divided into segments for the report.
Aquatic Life (habitat for fish and other aquatic life and wildlife)
All segments of the river and its tributaries are either fully supported or not assessed, except three tributaries (see Impaired Waterbodies below).
Fishing (fish consumption)
All segments are fully supported for fishing. DEEP has issued qualifications for consuming fish from the Willimantic River: for fish other than trout, there is an advisory to consume only one meal per month due to mercury (from acid rain).
Recreation
The 2010 Report reflects new standards required by the U.S. Environmental Protection Agency. Like many other waterbodies in the state, parts of the Willimantic River and its tributaries are now listed as “not supported” for recreation because of excess indicator bacteria in the water (see Impaired Waterbodies below). This status does NOT indicate increased amounts of bacteria. Instead, EPA has raised bacteria standards for supporting recreation. A waterbody must now be safe for swimming to be supported for recreation of any kind, including boating and fishing. The sources of the bacteria are unknown at this time, but Ct. DEEP is sampling rivers across the state to determine bacteria sources and remedies. Eagleville Lake is supported for recreation (there are different standards for impoundments).
Impaired Waterbodies List
- Segments that are considered impaired (not supported) for recreation due to excess indicator bacteria (E. coli): The main stem of the Willimantic River has two segments that are considered impaired for recreation: from the confluence with Tenmile River in Columbia/Lebanon upstream to the outlet of Eagleville Lake and from the inlet of Eagleville Lake upstream to the confluence with Bonemill Brook in Tolland.
- Tributaries that are considered impaired (not supported) for recreation due to excess indicator bacteria (E. coli): Hop River, Skungamaug River.
- Tributaries that are considered impaired for recreation due to excess indicator bacteria (E. coli) and/or impaired for aquatic life: Furnace Brook (segment in Stafford Springs for recreation due to bacteria and for aquatic life because it is a concrete channel) Ruby Lake outlet stream (segment in Willington for aquatic life due to accidental spill of diesel fuel at truck stop on I-84) Eagleville Brook in Mansfield for recreation due to bacteria and for aquatic life due to streambank modification and stormwater runoff from developed areas upstream).
Total Maximum Daily Load (TMDL) Projects
Impaired waterbodies can be remediated through an implementation plan (TMDL) and/or a watershed-based plan to address the cause of the water quality problem(s). The impaired areas listed above (except Ruby Lake outlet) are priorities for developing a TMDL.
Connecticut's DEEP has developed a Total Maximum Daily Load (TMDL) plan for Eagleville Brook (a tributary of the Willimantic River). Under this plan, the University of Connecticut has initiated activities to address excessive stormwater runoff into the brook to help restore its aquatic life. The University's CLEAR (Center for Land Use Education and Research) has studied the impervious surfaces on campus and has recommended long-term and short-term solutions to moderate the impact of stormwater runoff from these surfaces into Eagleville Brook. NEMO reports on the progress of the TMDL implementation and details of several types of stormwater management projects on campus.
The Thames River Basin Partnership has a detailed inventory of actions to implement the Eagleville Brook TMDL.