Denver County, CO Environmental Rules: Erosion Control (2026)

Construction sites in Denver must control erosion and sediment under multiple layers: (1) Colorado CDPS Stormwater Construction General Permit via CDPHE for any disturbance of 1 acre or more; (2) Denver's MS4 permit obligations under DRMC §56; (3) project-specific Erosion Sediment Control Plans (ESCP) required at building permit issuance. Standard BMPs include silt fences around downhill perimeters, straw wattles in swales, inlet protection on all storm drain inlets in and adjacent to the site, stabilized construction entrances (rock pads) to prevent track-out, concrete washout containment, and stockpile covers. Disturbed areas inactive for 14+ days must be temporarily stabilized. Denver DOTI inspectors perform site visits during active construction; contractor-led self-inspections also required weekly and after ≥0.5-inch rain events, documented in an SWMP binder on-site. Track-out onto public streets triggers a same-day cleanup obligation and is a top-cited violation. Final stabilization (vegetation 70% cover or hardscape completion) is required before NPDES permit close-out. Violations escalate quickly given federal Clean Water Act exposure.