Downey, CA Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing section
- Downey Municipal Code § 5703
- Default rule
- All non-storm water discharge to MS4 prohibited
- Named prohibited discharges
- Pool water, vehicle wash water, concrete slurry
- Enforcing officer
- Director or City Code Enforcement Officer
- Penalty
- Misdemeanor; each day is a separate offense
Summary
Downey bans dumping anything but rain into its storm drains. Municipal Code § 5703 prohibits illicit connections to the storm sewer system and makes every non-storm-water discharge illegal unless it falls under a narrow, permit-based exemption, naming pool water, vehicle wash water and construction slurry as specific examples.
§ 5703. ILLICIT CONNECTION AND ILLICIT DISCHARGE PROHIBITION. (a) No owner, responsible party, or person, shall use, allow, or suffer, an illicit connection to the MS4; and must therefore remove or terminate such illicit connection. (b) No person or responsible party shall cause, nor contribute, to the exceedance of water quality standards, nor impair attainable beneficial use objectives in receiving waters of the State. (c) All non-storm water discharges are prohibited unless they're identified in Part III.A of the MS4 Permit. (d) Illicit discharges that are prohibited from entering the MS4 shall include, but are not limited to, the following: (1) The discharge of wash waters to the MS4 from the cleaning of gas stations, auto repair garages, or other automotive service facilities; ... (5) The discharge of chlorinated or brominated, swimming pool or spa water and filter backwash or diatomaceous earth to the MS4; and (8) Dumping or disposal of materials into the MS4, other than storm water.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4807734; v5 updated 2026-01-27).
Full Breakdown
Chapter 7 of Article V, the Storm Water and Urban Runoff Pollution and Conveyance Controls chapter, sets Downey's drainage rules against the backdrop of the Los Angeles County NPDES Municipal Separate Storm Sewer System (MS4) Permit. Section 5703 is the operative prohibition. Subsection (a) bars any owner, responsible party or person from using, allowing or suffering an illicit connection to the MS4, and requires removing or terminating one that exists. Subsection (b) separately forbids causing or contributing to an exceedance of water quality standards or impairing beneficial uses of receiving waters.
A of the MS4 Permit, or are authorized by the LARWQCB's Executive Officer. Subsection (d) then lists concrete examples of illicit discharges the City treats as automatically prohibited, including wash water from cleaning gas stations, auto repair garages or automotive service facilities; runoff from mobile auto washing, steam cleaning or mobile carpet cleaning operations; runoff from areas where leaking machinery is repaired; discharge or wash-down from storage areas holding grease, oil, paint or hazardous substances; chlorinated or brominated pool and spa water and filter backwash; and concrete or cement-laden wash water from concrete trucks, pumps, tools and equipment.
Enforcement runs through § 5710, which designates Authorized Enforcement Officers (the Director or a City Code Enforcement Officer) to issue cease-and-desist orders, declares violations a public nuisance abatable by the City Attorney, and authorizes civil remedies including injunctions and cost recovery for investigation, monitoring and cleanup, on top of misdemeanor prosecution.
Violations & Fines
An illicit connection to the MS4, or a prohibited non-storm water discharge such as pool backwash, vehicle wash water, or concrete wash-out reaching a storm drain, violates § 5703 and § 5710. Violations are misdemeanors under Chapter 2 of Article I of the code, with each day of continuing discharge a separate offense, and the City can also pursue civil injunctions and recover its investigation and cleanup costs from the responsible party.
Frequently Asked Questions
Can I wash my car in my driveway in Downey?
Can I drain my pool into the street in Downey?
What happens if concrete wash-out runs into a Downey storm drain?
Sources & Official References
Other rules in Downey
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