2022 CEQ Annual Report

Water Quality

The Water of Long Island Sound               Warming and Rising Waters               Swimming               Clamming and Oystering               Drinking Water

Rivers, Lakes, and Estuaries

Climate Change Indicator



The Department of Energy and Environmental Protection (DEEP) assesses* water quality 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 designated use. Water quality in the state has improved over the last few decades as a result of protective laws, remediation efforts, and investment in wastewater treatment infrastructure. While there has been an increase in the number of river miles assessed, there has been little change in the percentage of assessed river miles that fully support aquatic life. In addition, there has been little change in percentage of assessed lakes and estuaries that “fully support” aquatic life in recent years.30

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 (2012 data**) and the stream/river miles (2020 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: *Section 305(b) of the Federal Clean Water Act (CWA) requires each state to monitor, assess and report on the quality of its waters relative to designated uses. **Based on data from the Connecticut Environmental Conditions Online (CT ECO).


30 DEEP, 2022 Integrated Water Quality Report to Congress; portal.ct.gov/DEEP/Water/Water-Quality/Water-Quality-305b-Report-to-Congress.