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 is subject to LA County MS4 NPDES permit requirements for stormwater management. New development and significant redevelopment must implement Best Management Practices (BMPs) for stormwater quality.
Downey Stormwater Management Rules
Some RestrictionsErosion Control
Grading and construction projects in Downey exceeding 1 acre require a Stormwater Pollution Prevention Plan (SWPPP). Erosion control measures must be in place during the rainy season per state and county requirements.
Downey Erosion Control Requirements
Some RestrictionsCoastal 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
Few 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
Portions of Downey fall within FEMA-designated flood zones, primarily along the Los Angeles River and Rio Hondo channels. The city participates in the National Flood Insurance Program and enforces floodplain development standards.
Downey Flood Zone & Floodplain Regulations
Some RestrictionsGrading & Drainage
Grading permits are required in Downey for significant earth-moving projects. The Engineering Division reviews drainage plans to ensure proper stormwater conveyance and prevent flooding of adjacent properties.
Downey Grading & Drainage Rules
Some RestrictionsLooking for Los Angeles County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Downey city rules.
Environmental Rules in Los Angeles County →