WASHINGTON — Controversial cuts in water deliveries to central California farms to protect endangered fish appear to be "scientifically justified" but still in need of further study, scientists have concluded in a report to be issued Friday.
In a politically sensitive study, the National Research Council determined two federal agencies had a "sound conceptual basis" for their actions protecting Chinook salmon, delta smelt and other endangered fish. The conclusion undercuts a common farmer criticism.
However, the 65-page report may give some ammunition, as well, to those skeptical of water delivery restrictions imposed by the Fish and Wildlife Service and National Marine Fisheries Service.
Notably, the scientists determined that predators, pollution and other "stressors" accounted for some of the fish lost in the Sacramento-San Joaquin Delta. Until now, farmers say they've been held solely responsible for the fish losses, costing them water.
"Based on the evidence the committee has reviewed, the committee agreed that the adverse effects of all the other stressors on the (protected) fishes are potentially large," the study's summary conclusion states.
Pointedly, Rep. Dennis Cardoza, D-Calif., added in a statement Thursday that "predator fish have been allowed to flourish while cuts have continued in the deliveries of irrigation water to the San Joaquin Valley."
By itself, the "Sustainable Water and Environmental Management in the California Bay-Delta" study will not compel any new decision one way or another. It is, though, one more step in a long-running dispute over the division of water between fish and farms.
The study is a second look at two "biological opinions" issued over the past two years by the Fish and Wildlife Service and National Marine Fisheries Services. The biological opinions are management decisions that protect species covered under the Endangered Species Act.
The National Research Council suggested the two different federal agencies could do a better job of coordinating their efforts.
"The lack of a systematic, well-framed overall analysis is a serious scientific deficiency," the report states.
Last year, a combination of drought and environmental protections meant farmers on the San Joaquin Valley's West Side only received 10 percent of their normal water allocation. This year, pushed politically and buttressed by a better snow pack, the Interior Department has declared the farmers can expect at least 25 percent.
Prompted by unhappy farmers, Democratic Sen. Dianne Feinstein and other California lawmakers had urged the Obama administration to request the study. Last year, Feinstein secured $750,000 to help fund the work by the research arm of the National Academy of Sciences.
In part, the study counsels patience.
"Reversing or even slowing the declines of the listed species cannot be accomplished immediately," the study notes. "Even the best-targeted methods of reversing the fish declines will need time to take effect."
The new study further notes "substantial uncertainty" remains over key technical details, such as precisely how much water must flow through the San Joaquin River for the protection of fish.
All told, the 15-member research committee identified a number of unresolved issues that the panel will continue studying through November 2011. These will include more detailed evaluation of the non-farm "stressors" contributing to the Delta's decline.
"The preliminary report presents a lot of information that there are a lot of other problems that affect the Delta," said Rep. Jim Costa, D-Calif.