It is likely that water scarcity in the delta will become increasingly severe, the report says. Failure to acknowledge this problem and craft plans and policies that address water scarcity for all needs has made delta water management more difficult than is necessary. The committee that wrote the report suggested establishing priorities for water use, accounting for trade-offs in decision making, optimizing the availability of existing water supplies, enforcing California's constitutional prohibition against non-beneficial and wasteful water use, and practicing water conservation, among other principles and guidelines.
Multiple environmental stressors -- such as dams; water pumping stations; introduced and invasive species; and changes in nitrogen and phosphorus concentrations and amounts, water flow, and habitat -- negatively affect five delta fishes listed as endangered or threatened, the committee said. Successfully rehabilitating the delta ecosystem by targeting how an individual stressor impacts a particular species seems doubtful. Therefore, hard decisions will need to be made about balancing risks for different water uses, such as allocating water to support economic activity, sanitation, or other needs. In addition, alleviating any one stressor alone is unlikely to reverse declines in these species, but opportunities exist to mitigate or reverse the effects of many stressors. To increase the likelihood that actions to rehabilitate the ecosystem are cost-effective, continued analyses, modeling, and monitoring will be needed, the committee noted.
Climate change is one of the most challenging and important issues confronting the management and rehabilitation of the delta ecosystem. It is expected to affect the physical and ecological structure and functioning of the delta as well as the availability of water in the state. For instance, assessments suggest that many species will be affected by changes in runoff f
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National Academy of Sciences