Water Quality

Water of Long Island Sound               Warming and Rising Waters               Swimming               Drinking Water

Rivers, Lakes, and Estuaries

A key factor in water quality is the amount of impervious surfaces in a watershed.

There are estimated to be 5,830 river miles in Connecticut. DEEP makes water quality assessments for each designated use (aquatic life, recreation, and fish consumption) for waterbodies in the state (rivers, lakes, and estuarine areas) as either fully supporting, not supporting, insufficient information, or not assessed, which characterizes whether or not the water is suitable for that use. While the quantity of river miles assessed has increased over time, the percentage of river miles that fully support the designated use has decreased for aquatic life and especially recreation since the last reporting period (2016).

Likewise, the percentage of estuaries that fully support the designated use has decreased slightly for aquatic life and recreation since the last reporting period (2016). Notwithstanding the fact that more than 88 percent of all assessed waterbodies of the state fully support fish consumption (2018), there is a statewide fish consumption advisory for all freshwater fish, except trout, due to atmospheric deposition of mercury and all estuarine waters have a fish consumption advisory on striped bass and bluefish due to PCB contamination.

_{Technical Note: Apparent fluctuations in year-to-year water quality results may be due to limitations in data collection and study design and not to widespread changes in water quality.}