Pomona, CA Environmental Rules: Stormwater Management (2026)

Adopted by Ordinance No. 4185 on June 2, 2014 to implement the federal Clean Water Act and the county's NPDES municipal stormwater permit, the LID Ordinance sets minimum design and management standards for new development and redevelopment. Sec. 74-314 lists the project types that trigger it: any development of one acre or more of disturbed area that adds over 10,000 square feet of impervious surface; industrial parks, commercial malls and parking lots at or above their own square-footage or space-count thresholds; retail gas stations and restaurants of 5,000 square feet or more; street and road construction of 10,000 square feet or more; and redevelopment projects that add, replace or alter 5,000 square feet or more of impervious surface on an already developed site.

Under Sec. 75-inch, 24-hour storm or the 85th-percentile 24-hour storm, whichever is greater, entirely on site by minimizing impervious area and routing runoff through infiltration, bioretention or rainwater harvest and use. Sec. 5 times the shortfall or fund an approved offsite mitigation or retrofit project. Sec. 74-331 puts the city engineer in charge of plan review, and any approved project must record a maintenance covenant with the Los Angeles County registrar-recorder before the city issues a certificate of occupancy, documenting every BMP, its location and its required inspection and maintenance frequency, with records kept for at least two years and produced to the city on request.