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

Significant Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Enforcing agency
Adams County Public Works
Core prohibition
No discharge but stormwater into MS4
Cure period
10 days after Notice of Violation
2nd offense fine
Minimum $500 per day
3rd+ offense fine
Minimum $750 per day
Effective date
November 13, 2017
Penalty statute
C.R.S. § 30-15-402

Summary

Adams County's MS4 illicit discharge ordinance bans putting anything but rainwater into the county's storm drains, ditches and detention ponds in the unincorporated area. Public Works enforces it through inspections, notices of violation and criminal citations, with fines that climb steeply for repeat offenders under the county's storm drainage code.

City-specific rules exist: Thornton, and Westminster have their own stormwater management rules that differ from Adams County's county-level regulations. If you live in one of those cities, check the city-specific page instead.

A. Prohibition of Illicit Discharges

1) No person shall discharge or cause to be discharged into the storm drainage system or watercourses any pollutants or waters containing any pollutants that cause or contribute to a violation of applicable Water Quality Standards, or Total Maximum Daily Load (TMDL), other than stormwater.

2) It shall be unlawful to cause pollutants to be deposited in such a manner or location as to constitute a threatened illicit discharge into the storm drainage system or Waters of the State.

Full Breakdown

Ordinance No. 11, adopted October 10, 2017 under Resolution 2017-471 and effective November 13, 2017, regulates what may enter unincorporated Adams County's Municipal Separate Storm Sewer System (MS4), meaning county-owned storm drains, roadside ditches, curbs, gutters, culverts and detention ponds. Section 5 bars any discharge other than stormwater into that system or into watercourses, and separately bars illicit connections such as sump pumps, wash water lines or sewage tied into a storm drain, including connections that predate the ordinance. A list of everyday exemptions covers landscape irrigation, air conditioning condensate, individual car washing, footing and roof drains, dechlorinated pool discharges, firefighting water and NPDES/CDPS-permitted discharges.

Adams County Public Works, through its Director and Stormwater Coordinator, administers the ordinance, may inspect any property in the unincorporated county, install monitoring equipment, and require Best Management Practices from anyone whose activity could pollute stormwater. Section 6 lets the Director suspend a property's MS4 access without prior notice if a discharge poses an imminent danger, and terminate access for ongoing noncompliance. Property owners along a watercourse must keep their stretch free of trash, debris and obstructions under Section 5's watercourse-protection clause. Anyone reporting a known or suspected release must notify the Director no later than the next business day, and immediately notify emergency dispatch for hazardous material releases.

Violations & Fines

Every day a property stays in violation is a separate offense. A Notice of Violation gives the owner ten days to abate; missing that deadline lets the Director seek a court warrant to enter and fix the problem, billing the owner plus a five percent inspection fee, which becomes a lien if unpaid after 60 days. Criminal prosecution under Section 30-15-402, C.R.S. carries a minimum $500-per-day fine for a second offense and $750 per day for a third or later offense.

Frequently Asked Questions

What can't I put into a storm drain in unincorporated Adams County?
Section 5 of Ordinance No. 11 prohibits any non-stormwater discharge, and lists exemptions such as landscape irrigation runoff, air conditioning condensate, footing and roof drains, dechlorinated pool water managed under state guidance, individual car washing, and firefighting or emergency utility repair water. Anything else, from paint rinse water to pet waste runoff, is illicit.
Who enforces the stormwater ordinance?
Adams County Public Works enforces the ordinance. Its Director, Stormwater Coordinator, or another designated staff member can inspect any property in the unincorporated county, install monitoring or sampling devices, and issue citations or summonses. If access to a property is denied, the Director can seek an administrative entry and seizure warrant from the courts.
Can the county cut off my property's storm drain access?
The Director can suspend a property's connection to the storm drainage system without prior notice when a discharge presents an imminent or substantial danger to health, the environment, or the MS4 itself. Reinstating access without the Director's prior approval is itself a violation of Ordinance No. 11.

Sources & Official References

Other rules in Adams County

All Adams County rules

Compare Adams County to another location·View the Colorado environmental rules overview

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