In the 1970s, the Los Angeles Department of Water and Power was forced by the California State Department of Health Services to improve the water quality of the Hollywood Reservoir; at first, LADWP proposed placing covers on both the upper and lower parts of the Hollywood Reservoir, but a coalition of neighborhood and community groups called Coalition to Preserve Open Reservoirs (CPOR) negotiated with LADWP to utilize another approach; after 1990, LADWP agreed to the creation of underground water tanks and a small filtration plant at the bottom of Mulholland Dam to create higher water purity standards.

PCAD id: 13695