ESTABLISHING A BASELINE FOR CONTAMINANT TRENDS IN CALIFORNIA RESERVOIRS: CASTAIC LAKE STATE RECREATION AREA, LOS ANGELES COUNTY

Castaic Lake, in Los Angeles County, is an emergency drinking water reservoir and a popular recreation area. Although there is a posted fish consumption advisory for mercury and PCBs, limited data are available for water quality at depth. This knowledge gap is a concern because in deep reservoirs, cold dense bottom water can lose contact with the atmosphere, leading to oxygen depletion and water quality degradation. We are characterizing the concentration and distribution of metals (e.g., Cu, Pb, Zn, Fe) in Castaic Lake and Pyramid Lake water and sediment to assess the influence of water column stratification on these contaminants. The tendency of metals to sorb to particles decreases in low oxygen environments. We hypothesize that metals in water near the water-sediment interface will be higher than in surface waters, with concentration spikes when oxygen is lowest. As global warming increases, density stratification in reservoirs may intensify as well. This project will therefore highlight potential concerns for reservoir contaminant cycling within this region.