San Joaquin Valley Evaporation Basins Impact Analysis

San Joquin Valley, California

Agricultural drainwater evaporation basins in the Tulare Basin had been shown to contain selenium and other metals in concentrations affecting the breeding, migrant, and wintering shorebirds and waterbirds using them. Integral staff were engaged to develop a cumulative impacts analysis and mitigation design for the Environmental Impact Report and Waste Discharge Permit conditions governing continued operation of the basins. The team documented contamination extent in basin water and soils, assessed cumulative effects across approximately 7,000 acres based on exposure risk and duration, and designed mitigation measures to limit bird exposure to contaminants of concern. The resulting impact avoidance and mitigation plan became the cornerstone for continued operation of the basins, and Integral staff continue to monitor and manage evaporation basins and mitigation wetland habitats for major farmers and drainage districts in the San Joaquin Valley, as they have for more than 25 years.