Irrigation drainage reduction

In a large area on the West Side of California's San Joaquin Valley, natural drainage is severely limited by impermeable soil layers. Irrigation drain water that percolates through the upper layers of soil has traditionally been collected by underground drainage systems and discharged into Kesterson Reservoir or the San Joaquin River, The discovery of high levels of selenium in the drain water in 1984 resulted in the closure of Kesterson and plugging of the 80-mile-long San Luis Drain leading to it. Without a readily available, environmentally-safe alternative for drain water disposal, many growers on the West Side are farming land without drainage. Minimizing irrigation drainage and deep percolation is of paramount importance. One approach to the problem is to improve the efficiency of irrigation systems in the region and thereby reduce the volume of water that needs to be removed. The following articles report on some ways University of California scientists are studying to achieve this goal: more efficient, better managed irrigation systems, reuse of irrigation drain water, and new irrigation techniques.