Environmental Rules in Downey, CA (2026)
5 verified environmental rules for Downey, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
Stormwater Management
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.
Downey Storm Drain Discharge Prohibition
Significant RestrictionsDowney, CA, Municipal Code § 5703
§ 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 rec...
Erosion Control
Any construction, commercial or industrial project in Downey that needs a state NPDES stormwater permit must have it before work starts. Municipal Code § 5704 requires keeping the Construction General Permit, a site-specific SWPPP and stormwater quality data on hand for inspection, so erosion and sediment controls are documented, not optional.
Downey Construction Stormwater Permit Rule
Significant RestrictionsDowney, CA, Municipal Code § 5704
§ 5704. CONTROL OF POLLUTANTS AND RUNOFF FROM SITES REQUIRING A STORMWATER ACTIVITIES PERMIT. (a) It shall be a violation of this chapter for any person or entity, required by governmental law to obtain a NPDES stormwater activities permit, to conduct a construction, commercial, or industrial activity in the City of Downey, without the appropriate Construction General Permit (CGP) or Industrial...
Coastal Development
Downey is an inland city approximately 12 miles from the coast and is not within the California Coastal Commission's jurisdiction. Coastal development regulations do not apply.
Downey Coastal Development Rules
Some RestrictionsCA Coastal Commission - Coastal Zone Boundary (Coastal Act of 1976, PRC Sec. 30103)
Coastal Act of 1976). PRC Section 30103(b) directed the Coastal Commission to prepare and adopt more detailed 1:24,000 scale Coastal Zone Boundary (CZB) maps, which occurred March 1, 1977. These 161 adopted maps provide the official basis for all other representations of the landward CZB. The digital version of the CZB created by developing this data is a conformed copy of the official boundary...
Flood Zones
Any new construction, development, or substantial improvement inside a Downey special flood hazard area needs a building or grading permit before work starts, under Municipal Code § 8710.01. The floodplain chapter applies citywide to every area FEMA maps as a special flood hazard on the City's July 6, 1998 Flood Insurance Rate Map, and violations are a misdemeanor under § 8700.07.
Downey Floodplain Development Permit Rules
Some RestrictionsDowney, CA, Municipal Code § 8710.01 (Permits Required); §§ 8700.04, 8700.07
§ 8700.04. APPLICABILITY. The floodplain management provisions of this chapter shall apply to all areas of special flood hazards within the jurisdiction of the City of Downey. ... § 8710.01. PERMITS REQUIRED. A building or grading permit shall be obtained before new construction or development or substantial improvement begins within any area of special flood hazards, established in Section 870...
Flood Elevation Requirements
New residential construction inside a Downey special flood hazard area must have its lowest floor, including any basement, elevated above the highest adjacent grade, per Municipal Code § 8710.06(c). In an AR zone with a mapped base flood depth, that means elevating to the depth shown on the FIRM, or at least two feet if no depth is listed, then certifying the finished elevation to the Building Official.
Downey New Construction Flood Elevation Rules
Some RestrictionsDowney, CA, Municipal Code § 8710.06(c) (Elevation and Floodproofing)
(c) Elevation and Floodproofing. (1) New residential construction shall meet the standards of Section 8710.06 and shall have the lowest floor, including basement, elevated as follows: a. In the AR (with base flood depth) zone, elevated above the highest adjacent grade at least as high as the depth number specified in feet on the FIRM, or at least two feet (2') if no depth number is specified. b...
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