In 1998 the City of Los Angeles passed a stormwater ordinance (LAMC 64.70) which prohibits the entry of illicit discharges into the municipal storm drain system and gives the City local legal authority to enforce the NPDES permit and take corrective actions with serious offenders. Any commercial, industrial or construction business found discharging waste or waste water into the storm drain system may be subject to legal penalties.

To ensure that local businesses are doing their part in keeping Los Angeles safe, healthy and clean, stormwater inspectors conduct annual inspections at local industrial and commercial businesses, including restaurants, gas stations and vehicle maintenance facilities whose daily business activities may negatively impact regional water quality.

In 2011 the City of Los Angeles passed a Low Impact Development (LID) ordinance which amends LAMC 64.70 and requires development and redevelopment projects to mitigate runoff in a manner that captures rainwater at its source utilizing natural best management practices such as rain barrels, permeable pavement, storage tanks and infiltration swales.