As Los Angeles’ population began to grow rapidly at the beginning of 20th century, rainwater that was once absorbed by miles of undeveloped land began to runoff the newly paved and developed areas, leading to an increased amount of water flowing into Los Angeles’ local creeks and rivers. These natural waterways could not contain the increased amount of water and the region experienced catastrophic and deadly floods in the late 1920s. In response, the Army Corps of Engineers lined the Los Angeles River and Ballona Creek with concrete in the 1930s and 40s and initiated the development of an underground urban drainage system. The result was a complex 1,500-mile system comprised of more than 30,000 catch basins and 100 miles of open channels.
Amendments to the federal Clean Water Act result in a National Pollutant Discharge Elimination System (or NPDES) Permit for storm water similar to that for waste water treatment plants.
The California Regional Water Quality Control Board issues the first NPDES municipal stormwater permit to the County of Los Angeles and 84 incorporated cities, including the City of Los Angeles. The City of Los Angeles’ establishes its own stormwater program, which is a part of the Department of Public Works. The Watershed Protection Division is responsible for the development and implementation of stormwater pollution abatement projects and programs.
The Porter-Cologne Water Quality Act mandates water quality standards for surface and groundwater in California, requiring states to establish a priority ranking for impaired waters and to develop and implement Total Maximum Daily Loads (or TMDLs).
The City of Los Angeles passes a stormwater ordinance (L.A.M.C. 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.
Courts issue a consent decree requiring all TMDLs in the Los Angeles region by adopted within 13 years.
The Los Angeles Regional Water Quality Control Board adopts a Los Angeles municipal stormwater permit, including TMDL implementation requirements.
US Environmental Protection Agency begins approving various TMDLs for multiple watersheds including trash for LA River and Ballona Creek, wet and dry weather for Santa Monica Bay Beaches and bacteria for Marina del Rey Harbor and Mother’s Beach, among others.
Los Angeles voters pass Measure O, a general bond measure that authorizes $500 million in bonds to build improvements designed to address the regulatory requirements of the federal Clean Water Act and improve water quality, protect public health and the environment. Measure O helps to provide funds for TMDL compliance and projects to remove trash, bacteria and other pollutants from local rivers, lakes, beaches and the ocean.
The City of Los Angeles passes a Low Impact Development ordinance, which amends L.A.M.C. 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 to use water.