Municipal Separate Storm Sewer System (MS4) Permit

The Environmental Protection Agency (EPA) issued the City of Lewiston and Lewis Clark State College the National Pollutant Discharge Elimination System (NPDES) Phase II Municipal Separate Storm Sewer System (MS4) permit which became effective on November 1, 2020 and expires at midnight on September 20, 2025. The final permit modification became effective August 1, 2021.

The MS4 permit requires permittees to develop and implement a comprehensive Stormwater Management Program which includes pollution prevention measures, treatment techniques, monitoring, and other appropriate measures to control the quality of discharge to storm drains which flow to waters of the United States.

Need to report illicit discharges, illicit connections, or illicit dumping activity? 

To report a release of materials that pose an immediate threat to life or a significant threat to the environment, please notify the following agencies immediately:

  1. Idaho Department of Environmental Quality (DEQ) via emergency dispatch services (911);
  2. The Stormwater Division at 208-298-3900 or; and
  3. Complete this online form.

Related Documents