Longmont, CO Environmental Rules: Stormwater Management (2026)
Key Facts
- Discharge rule
- MS4 ban, few exemptions
- Reporting
- Report hazardous release within 24 hrs
- Criminal penalty
- Up to $999 fine, 180 days jail
- Civil penalty
- Up to $500 per day
Summary
Longmont bans any non-stormwater discharge into its municipal storm sewer system, covering hazardous chemicals, construction runoff and other pollutants, with narrow listed exemptions and daily civil penalties for violations.
Non-stormwater discharges to the city's MS4 are prohibited. Illegal non-stormwater discharges include, but are not limited to, discharges that: 1. Cause or contribute to violations of the city's MS4 general permit; 2. Cause or contribute to any blockages of or damage to the MS4; 3. Constitute a fire or explosion hazard; 4. Contain any toxic or hazardous material, including, but not limited to, pathogens, chemicals and automotive fluids and hazardous waste as defined in 40 CFR 261.3.
Full Breakdown
Longmont Municipal Code § 14.26.050 prohibits non-stormwater discharges to the city's MS4, including anything that violates the MS4 general permit, blocks or damages the system, poses a fire hazard, or contains toxic, hazardous or radioactive material, and specifically bars discharges resulting from construction activities like earthwork, paving or material storage. A short exempt list covers things like AC condensation, residential car washing and dye testing done with agency notice. Anyone responsible for a release must contain and clean it up, and report hazardous releases to emergency dispatch immediately or nonhazardous ones to the director within 24 hours.
Violations & Fines
Violating § 14.26.050 is a strict-liability offense under § 14.26.160, punishable by a fine up to $999 or up to 180 days imprisonment per day of violation, plus a separate civil penalty of up to $500 per day under § 14.26.210.
Frequently Asked Questions
What counts as an illegal discharge in Longmont?
What happens if I discharge something illegal into a storm drain in Longmont?
Sources & Official References
Other rules in Longmont
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Stormwater Management in Nearby Cities
How other cities in Boulder County handle stormwater management.