The CT revised MS4 general permit applies to all municipalities that have at least 1,000 people within an "Urbanized Area". Urbanized areas are determined based on the 2010 U.S. Census. This includes 113 municipalities who were subject to the previous permit plus 8 new municipalities for a total of 121 towns. It also includes all state and federal institutions that operate a separate storm sewer system.

CT MS4 Municipalities

There are 8 new towns which join the original 113 CT municipalities regulated by the permit. The City of Stamford is regulated by its own individual MS4 permit.

CT MS4 Institutions

The 2016 MS4 General Permit also applies to state and federal facilities that:

1. operate a stormwater system,
2. consist of more than one building, and
3. have an average daily population of 1,000 people or more.

This does not include the Department of Transportation which will be subject to its own permit.