In 1979. the California Safe Drinking Water Act established a new turbidity limit of 0.5 turbidity unit for drinking waters. To meet this new standard at the Owens River Aqueductplantin Los Angelesi aprocessinvolvingpreozonation and direct filtration was tested and selected. In addition to providing water which meets the required turbidity standard, the ozone process reduces THM levels by about 50%, allowsfiltrationrates of 15 gpm/ft2, reducescoagulation requirements, increases the removal of organics, thus reducing final chlorination requirements, and provides the most cost–effective reduction of levels of taste, odor, and color. The new Los Angeles water treatment plant will be on–line in 1986.