In the midst of a nationwide drought, farmers in California's San Joaquin Valley are wasting as much as 55 percent of the irrigation water they use, a University of California report says.

The report said much of the water applied to western San Joaquin Valley crops is lost below the root zone because farmers are applying too much water.The growers waste vast amounts of water because they do not irrigate properly, have inefficient irrigation systems or do not worry about wasting federally subsidized water because it is so cheap, the report said.

The wasted irrigation water becomes salty drainage water laden with selenium and other trace elements that have created a major disposal problem for western valley agribusiness, the report said.

The report comes as western valley cotton farmers are under increasing pressure to reduce the amount of drainage water.