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

Ordinance No. 2012-4 implements Boulder County's federal and state stormwater discharge permit obligations under the Clean Water Act. Section 6(A) bans discharging, or causing to be discharged, any pollutant into the storm drainage system or a watercourse that causes or contributes to a water-quality violation, and separately makes it unlawful to deposit pollutants anywhere they threaten such a discharge; pollutants no longer contained in a pipe or tank are presumed to be a threatened discharge unless actively being cleaned up. Section 6(B) bans illicit connections to the storm drainage system outright, including connections made years ago that were legal when installed.

A short list of exemptions in Section 6(C) covers things like water line flushing, lawn irrigation, dechlorinated pool water, and non-commercial vehicle washing, plus discharges already covered by an NPDES or CDPHE permit. Property owners also carry affirmative duties under Section 6(D): keeping paved parking lots and drives clean of pollutant buildup, containing leaks from equipment maintenance, and storing construction materials to minimize runoff. Boulder County Public Health (BCPH) administers and enforces the ordinance, can enter property to investigate suspected violations, and can seek an administrative entry and abatement warrant when a stormwater violation goes unabated, assessing cleanup costs as a lien on the property, plus 5% for inspection costs and a 10% collection penalty if unpaid.

S. Title 30, Article 15, lets BCPH recover its attorneys' fees and costs, and deems any ongoing violation a public nuisance that can be summarily abated at the violator's expense.