Denver County, CO Environmental Rules: Stormwater Management (2026)

Denver's stormwater system is operated by the Department of Transportation and Infrastructure (DOTI) Wastewater Management Division under a federal NPDES Municipal Separate Storm Sewer System (MS4) permit from EPA Region 8 and CDPHE. DRMC §56 and the Denver Storm Drainage Design Criteria Manual (most recent update 2021) set engineering standards. New development and substantial redevelopment (typically >10,000 sq ft disturbed) must submit a Drainage Report and install water quality capture volume (WQCV) facilities — detention/retention ponds, bioretention, permeable pavement, or rain gardens — to treat the first flush. Erosion and sediment control plans are required during construction. Property owners pay stormwater fees based on parcel impervious area, billed quarterly with sewer charges; residential rates run ~$11-$13/month (2024). Illicit discharge (pouring anything other than clean stormwater into storm drains) is prohibited. The Platte to Park Hill Stormwater project (~$300M) addressed historic flooding in Cole, Clayton, and Elyria-Swansea neighborhoods. Downtown and older NE Denver sit in parts of the 100-year FEMA floodplain along the South Platte and Cherry Creek.