Prior to the 1940S, spring-run chinook salmon were the dominant salmon run in the SAN joaquin river (SJR) basin

From the 1940S through the 1980S, major changes in water use and delivery occurred. The cumulative result of these actions (e.g., water diversions and habitat degradation) have been the extirpation of self-sustaining stocks of spring-run chinook salmon and the near extirpation of steelhead (now listed as threatened by the federal endangered species act). These actions also have resulted in substantial curtailment of fall-run chinook salmon production during the latest multi-year droughts. Along with declines in both the salmon and steelhead runs has been the reduction of angling opportunity. Resource managers have had to shorten seasons and reduce bag limits to protect SJR salmon and steelhead stocks. Salmon and steelhead populations in the SJR basin appear to rise and fall in connection with wet and dry year cycles. Since the SJR basin, in recent history, can produce tens of thousands of adult salmon, IT is believed that greater, and more frequent, production of large numbers of adult salmon and steelhead is possible. Substantial opportunity for restoration of inland and ocean sport fisheries exists if in-stream habitat quality and quantity can be improved.DAM operations on the SAN joaquin, stanislaus, tuolumne, and merced rivers since the 1940S have significantly altered hydrologic patterns and the amplitude of channel forming stream flow. Cumulatively private, state, and federal water diversions along the rivers and in the sacramento-SAN joaquin estuary increase mortality rates for various salmonid life stages resulting in lowered adult salmon and steelhead production. These water projects also blocked the natural downstream movement of sediment, which form spawning and rearing habitat for anadromous fishes (salmon, steelhead, lamprey and sturgeon).fall spawning flows are inadequate to maintain good water quality and to safely guide adults upstream. Spring stream flows are inadequate to provide optimum rearing conditions and optimum survival levels during outmigration periods on an annual basis. Impingement, entrapment and the confusion and delay of young salmon during rearing and outmigration further exacerbates mortality rates. Also, water quality changes associated with agricultural drainage water may further reduce juvenile salmon production. IT is believed that dramatic increases in juvenile production, out migration survival, and eventual adult salmon and steelhead escapement, are possible through a combination of flow and habitat improvements.