Sustaining salmon on the Trinity River, California : a case study on conflicting water uses

Abstract

<p>In 1955, Congress authorized the construction, operation, and maintenance of the Trinity River Division (TRD) as part of California's Central Valley Project (CVP). By 1963, the Trinity River was physically diverted via a series of manmade dams, reservoirs, power plants, pipelines and tunnels before merging with the Sacramento River waters and veering into California's Central Valley. Currently, the primary goals of the TRD are supplying water for irrigation and domestic use and generating power. Economic feasibility has been the primary funding criterion; environmental considerations were added only after Congress mandated measures to insure the preservation and propagation offish and wildlife. Federal trust responsibilities for tribal fishery resources were later added as a decision criterion. In the 1970's, California Department of Fish and Game officials concluded that the TRD's 109 mile salmon habitat diversion, created by dam construction and subsequent sustained, very low downstream river flows, caused fish stock declines. Scientists concluded that variable flows of sufficient size could clean spawning gravels, build gravel bars, scour sand out of pools, oxygenate water, hold riparian encroachment at bay, provide adequate temperature and habitat conditions for Chinook salmon at different life stages, and perform many other ecological functions necessary to restore anadromous fish stocks and the natural alluvial plain. Many acts, environmental impact statements, decisions, and memorandums have been signed in an effort to restore the fisheries and fish habitats in the Trinity River basin to the level that existed prior to the construction of the TRD. None of the legal remedies employed prevented a massive (33,000) salmon kill in 2002. Today's policy makers must continue to weigh the legal, social, environmental, and economic demands. This case illustrates the continuing struggle to strike a balance between competing environmental, economic, legal, and social pressures on California's limited fresh water. It also highlights the need for increased interdisciplinary reporting to capture the non-traditional variables that help policy makers support environmentally sound solutions.</p>