Report: Delta water restrictions sound, but need more study

Tough new restrictions on Delta water supplies are for the most part scientifically sound, although some of the details should be more carefully analyzed, a panel of experts concludes in a report to be released today.

The National Research Council's review was prompted by Sen. Dianne Feinstein, who in September asked for it at the request of San Joaquin Valley farmers hurt by three dry years and the effect of new rules to prevent fish from going extinct.

The report, which was obtained by Bay Area News Group late Thursday, appears unlikely to do immediately what farmers were hoping for — ease regulatory restrictions and increase water supplies.

However, it does allow that factors other than water pumping could be having a large effect on dwindling fish populations, and the panel plans to look more thoroughly at those factors in a second report next year.

Of the new requirements, most were determined to be sound and justified, at least in concept. But the rationale behind some of the specifics in the regulations should be developed more thoroughly, the report says.

The report does not support assertions that the new regulations are not working because fish populations have not rebounded since they were put in place.

"The committee concludes that reversing or even slowing the declines of the listed species cannot be accomplished immediately.

Even the best-targeted methods of reversing the fish declines will need time to take effect amid changing environmental conditions such as multiyear droughts and continued pressures on the system from other human-caused stresses," the report's summary says.

The panel looked at a number of alternative regulations that might provide equal protection for endangered fish at less cost to water users, but it found that none of them were sufficiently developed to be warranted.

At issue are two biological opinions that act as permits for massive water projects that move water through the Delta to many parts of California.

The opinions were issued in December 2008 and June 2009 after a federal judge ruled the earlier permits were insufficient to prevent Delta smelt and runs of salmon, steelhead and green sturgeon from going extinct.

Those new permits cut into water supplies last year that were depleted by drought, and they are making a recovery from drought this year more difficult for some water agencies.