Water Quality

The Municipal Separate Storm Sewer System (MS4) program was created to help maintain and improve the quality of waterways by reducing the pollutant discharges that flow into them with stormwater runoff. 
The Louisville MS4 program is regulated under the Kentucky Pollutant Discharge Elimination System (KPDES) permit issued by the Kentucky Division of Water (DOW) to MSD and co-permittees.  MSD is the lead administrative agency, and the co-permittees include: 

Explore the links below to learn more about the activities and programs associated with the MS4 permit.

The primary federal regulation pushing communities towards the goal of “fishable and swimmable water” is the Clean Water Act (CWA). The CWA, enacted in 1972, was amended in 1987 to mandate that the EPA address non-point source pollution in stormwater runoff. The MS4 permit is a result of the 1987 amendments. Sections of the CWA, which specifically are relevant to stormwater, address:

  • Regulation of stormwater discharges
  • Water quality standards for water bodies receiving stormwater runoff
  • Implications of non-attainment of water quality standards

MS4 Assessments and Reports

Current MS4 Permit

Current SWQMP 

Current MS4 Annual Report

Current State of the Streams