Innovative Drainage Management Practices in California

Agricultural lands of the westside of the San Joaquin Valley in California are underlain by a low permeability clay layer causing a shallow water table to rise toward the soil surface. The soils and shallow groundwater contain naturally occurring trace elements. High concentrations of trace elements, such as selenium, pose a potential hazard to fish and wildlife. About 400,000 hectares of lands have shallow groundwater within 3 m from ground surface. Tile drains have been installed in approximately 50,000 hectares of affected lands to lower the water table and remove the salts from plant root zone. The Valley consists of the San Joaquin River Basin in the north and the Tulare Lake Basin, a closed basin, in the south. Drainage management measures have been developed and implemented to control salinity, shallow water table, and trace elements. Innovative drainage management practices implemented, in the San Joaquin River Basin and the Tulare Lake Basin, to protect the fish and wildlife from toxic trace elements in drainage water are discussed.