Water Quality

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

Rivers, Lakes, and Estuaries

Quick Summary - dash dash dashClimate Change Indicator


Water quality shows little signs of improvement.

There are estimated to be 7,772 river miles, 72,509 acres of lakes, and 611.91 square miles of estuarine waters in Connecticut. Connecticut’s waterbodies (rivers, lakes, and estuarine areas) provide several key functions, such as the redistribution of sediment and nutrients vital to aquatic habitats; provision of drinking water, power, and irrigation; essential habitat for an abundance of diverse plants and animals, including migrating birds and waterfowl.33

The Department of Energy and Environmental Protection (DEEP) makes water quality assessments for each designated use (aquatic life, recreation, and fish consumption) for some waterbodies in the State as either fully supporting, not supporting, insufficient information, or not assessed, which characterizes whether or not the water is suitable for that use. While there has been in increase in the miles of assessed rivers to all those tracked by DEEP, there has been no appreciable change in the percentage of assessed waterbodies (rivers, lakes and estuaries) that fully support aquatic life goals since 2018.34

Impervious cover, wastewater treatment outflows, stormwater drainage systems and over land flow are primary factors in the transport of pollutants to surface waters!

The Council assessed the relationship between the percent of impervious cover and the number of stream/river miles (2018 data) that do not support aquatic life or recreation for each impervious cover grouping. The ratio of the number of impaired stream/river miles divided by the total area of drainage basins for each impervious cover grouping highlights the relative impact that impervious cover has on water quality.


Goal: Attainment, wherever possible, of “water quality, which provides for the protection and propagation of fish, shellfish and wildlife and provides for recreation in and on the water”.

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. 


33 DEEP, GC3 Final Report: Working & Natural Lands Working Group - Rivers Sub-Working Group; portal.ct.gov/-/media/DEEP/climatechange/GC3/GC3-working-group-reports/GC3-WNLWG-Rivers-Final-Report-11-20-20.pdf
34 DEEP, 2020 Integrated Water Quality Report - September 2020; portal.ct.gov/DEEP/Water/Water-Quality/Water-Quality-305b-Report-to-Congress.