Small MS4 Storm Water NPDES Draft Permit Issued By MPCA

The Minnesota Pollution Control Agency (MPCA) has released a draft the National Pollutant Discharge Elimination System (NPDES) State Disposal System (SDS) General Permit (MNR040000) for discharges of stormwater associated with small Municipal Separate Storm Sewer Systems (MS4s). Approximately 235 MS4s will be subject to the reissued NPDES/SDS General Permit. The permit requires MS4s to develop and implement a Stormwater Management Plan (SWMP) that is designed to reduce the discharge of pollutants from their storm sewer system and to protect water quality. The SWMPs must include Best Management Practices (BMPs) for six minimum control measures that are set forth in the NPDES Program regulations 40 Code of Federal Regulations § 122.34 (a) and (b). NPDES/SDS General Permit for Small Municipal Separate Storm Sewer Systems (or MS4s)

The draft general permit that MPCA proposes to reissue includes several modifications from the existing general permit, which expires on May 31, 2011. The MPCA has modified the existing NPDES/SDS General Permit to meet federal and state requirements for impaired waters and to address several main issues the MPCA identified as needing revision and/or clarification. The draft permit includes revised requirements for MS4 mapping, illicit discharge detection and elimination, construction stormwater erosion and sediment control, and post-construction stormwater management. The draft permit also includes new requirements for impaired waters covered by an EPA approved Total Maximum Daily Load (TMDL).

Interested persons can submit written comments on the draft permit. The public comment period begins May 31, 2011 and ends on July 15, 2011.

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