Skip to main content
U.S. flag

An official website of the United States government

Agricultural drainwater effects on wildlife in central California

January 1, 1995

In California's San Joaquin Valley and in numerous other agricultural areas in the western U.S., irrigation wastewater may accumulate in confined shallow aquifers, eventually rising to levels that adversely affect crops. To sustain long-term agricultural  productivity in these regions, systems for the drainage and disposal of this subsurface wastewater must be installed.1,2 the drained water may contain an array of soluble chemicals that have been applied to the crops, as well as those that have been leached from native soils. Agricultural drainwater is frequently disposed of by discharging it to surface aquatic systems where these constituents may be directly toxic to aquatic organisms, or they may bioaccumulate through the aquatic food webs upon which birds and other wildlife feed. The focus of this chapter is research conducted since 1983 to assess the effects of wildlife exposure to subsurface agricultural drainwater in the San Joaquin Valley.

Agricultural drainwater is discharged primarily to tributaries and wetlands of the San Joaquin River system or, especially in the southern San Joaquin Valley, to evaporation ponds.3 Because of high nutrient content in the drainwater, evaporation ponds have high levels of biological productivity and provide an abundant food supply for aquatic birds. Aquatic birds (primarily waterfowl and shorebirds) have been the main focus of wildlife research at the evaporation ponds, and at managed wetlands (primarily hunting clubs) within the San Joaquin River system, but mammals, snakes, and frogs have also been studied. Findings of those studies are summarized in this chapter. Other studies have been conducted on fish and aquatic invertebrates in areas receiving agricultural drainwater, but in this review those findings are described only as they relate to dietary exposure of wildlife.

Publication Year 1995
Title Agricultural drainwater effects on wildlife in central California
Authors Harry M. Ohlendorf, Roger L. Hothem
Publication Type Book Chapter
Publication Subtype Book Chapter
Index ID 5210575
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center; Western Ecological Research Center