Municipal Stormwater

The General Permit for the Discharge of Stormwater from Small Municipal Separate Storm Sewer Systems (MS4 General Permit) is the product of a mandate by the U.S. Environmental Protection Agency (EPA) as part of its Stormwater Phase II rules in 1999. This general permit requires each municipality to take steps to keep the stormwater entering its storm sewer systems clean before that stormwater enters water bodies. One important element of this permit is the requirement that towns implement public education programs to make residents aware that stormwater pollutants emanate from many of their everyday living activities, and to inform them of steps they can take to reduce pollutants in stormwater runoff. The Annual Report template is available below. Please note that there are two versions: one for 2004 MS4 permittees and one for 2017 MS4 permittees (8 new towns and all institutions). DEEP strongly recommends the use of these templates but alternate formats will be accepted as long as all the required information is provided. As a reminder, the Annual Report should be completed and posted for public review/comment by February 15th and submitted to DEEP by April 1st.
Department of Transportation (DOT) Separate Storm Sewer System General Permit
The Department of Transportation submitted Application No. 201904533 on March 25, 2019 for the Discharge of Stormwater from Department of Transportation Separate Storm Sewer Systems (DOT MS4). A copy of the registration can be requested by emailing DEEP at
Town by Town Water Quality Factsheets

The factsheets below provide a variety of water quality data in various formats for every city, town, or borough in Connecticut.

Related Information

Stormwater Management

Content Last Updated October 9, 2023