Perform hydrology and sedimentation studies; collect stream flow, precipitation, and
evaporation data; forecast runoff; analyze flood flows and take well measurements;
manage reservoirs, debris basins and disposal areas; and prepare maps of watersheds
burned by brush fires and potential mud flow areas.
Develop and direct the operation of the County's dams, spreading grounds, and seawater
barriers; gather and disseminate hydraulic and hydrological data; create hydrologic
computer models and build physical hydraulic models; perform frequency analysis of
rainfall and runoff; and perform studies and improvement planning on facilities under its direction;
Monitor and analyze water quality for surface and underground water
to protect County flood control and water conservation facilities and to
prevent contamination of the County's groundwater resources.
Operate and maintain 
Conserve each year in Los Angeles County an average of 220,000 acre-feet of local storm
water runoff that would otherwise waste to the Pacific Ocean. This amount, valued conservatively
at over $73 million, consists of direct storm runoff and post-storm releases from the dams. The
water flows to
27 groundwater recharge areas, or spreading grounds,
consisting of natural river bottoms and spreading basins and pits. During non-storm periods, the
artificial recharge program is supplemented by spreading almost 75,000 acre-feet of untreated
imported water and 50,000 acre-feet of reclaimed water.
Operate and maintain three seawater barriers in Los Angeles
County. These barriers inject treated imported water into the freshwater
aquifers along coastal areas to prevent the intrusion of salt water inland.
The aquifers protected by the barriers supply nearly 20 percent of the
water used in Los Angeles County.