Independent researchers said Friday that restrictions on water deliveries to California's farm belt meant to protect threatened fish can be scientifically justified, a finding sure to temporarily relieve the state's salmon industry and displease many farmers.
But they say more evidence is needed to reinforce when such pumping restrictions should occur.
The National Research Council, at the request of California lawmakers and the Obama administration, reviewed federal efforts to protect threatened fish like the Delta smelt and salmon.
Some lawmakers were hoping the review would alter those efforts and allow for more pumping of water from the Sacramento-San Joaquin Delta to parched farms.
Instead, the panel calls for better monitoring so that restrictions can be adjusted as needed to minimize the effect on farmers.
Pumping stations divert water from the California Bay-Delta to cities in Southern California as well as to farmers in the Central Valley, a region that grows much of the nation's produce. To protect native fish, federal agencies have ordered reduced pumping from the vast estuary since 2008.
The restrictions, combined with a three-year drought, have forced farmers to fallow thousands of acres and cities to impose severe water restrictions.
The committee concluded that in winter, a high level of pumping probably adversely affects smelt, but the data doesn't permit a "confident assessment of the benefits fish receive" from restricted pumping.
"As a result, the implementation of this action needs to be accompanied by careful monitoring, adaptive management, and additional analyses," said the 15-member panel.
The researchers also looked at whether other options might provide equal or greater protection for fish, while also giving farms more water. But the committee found none that had received sufficient evaluation. It will consider alternatives in more detail in a second report.
