Federal wildlife officials on Monday released new restrictions on pumping water from Northern California, further tightening the spigot on flows to Southern California cities and San Joaquin Valley farms.
The curbs, intended to keep the tiny delta smelt from extinction and stem the ecological collapse of California's water crossroads, could in some years cut state water deliveries by half.
"The water supply is becoming less certain," state water resources Director Lester Snow said.
The cutbacks will vary depending on conditions in the Sacramento-San Joaquin River Delta, the smelt's only home and a major source of water for the majority of Californians.
In a typical year, the smelt protections will slash California State Water Project deliveries 20% to 30% -- essentially maintaining the level of cuts ordered this year by a federal judge. Under the worst conditions, that figure could climb to 50%.
The limits come on the heels of two dry years, growing concern over diminished supplies from the Colorado River and a biological meltdown in the delta east of San Francisco.
"We're going to keep doing this until we do a long-term fix in the delta," said Snow, complaining that the federal action placed too much of the blame for the smelt's problems on the huge delta pumps that send water south.
Chemical contamination, invasive species, power plant operations and climate are all hurting the delta, he said.
Federal scientists say pumping has altered the hydrology and salinity of the delta and as a result, its suitability as a wildlife habitat. The pumps are so powerful that they reverse delta water flows, carrying fish to the pumps.
The smelt has become the emblem of the delta's environmental troubles. But it is just one of several delta fish species in trouble. Recreational and commercial fishing for chinook salmon, which migrate through the delta to the Sacramento River, was banned this year because the fall-run population was so low.
The new restrictions are contained in a biological opinion issued by the U.S. Fish and Wildlife Service. The 410-page document deals with the operation of the federal Central Valley Project and the State Water Project, California's two biggest water systems.
Ruling in one of a host of lawsuits that have been filed by environmental groups, U.S. District Judge Oliver Wanger last year threw out an earlier opinion prepared by the service that concluded the projects wouldn't jeopardize the smelt's continued existence.
Wanger called that finding "arbitrary, capricious and contrary to law," ordered the agency to prepare a new one and imposed a set of interim pumping curbs that reduced the amount of water exported from the delta this year by enough water to supply more than 1 million households.
The new opinion, released by fish and wildlife's Sacramento office, reversed the agency's stance, essentially continuing the temporary curbs and adopting additional ones to improve smelt habitat and keep the fish away from the pumps.
"This is a major new reduction in water deliveries that will impact families, businesses and farmers throughout California," said Laura King Moon, assistant general manager of the State Water Contractors.
The state project, which will be the most affected, provides about a third of the Southland's urban water. The rest comes from the eastern Sierra, the Colorado River, local groundwater reserves and reclaimed supplies.
An ongoing drought in the Colorado basin has cut deliveries of surplus water that Southern California has long depended on. And a statewide drought has depleted reservoirs the length and breadth of California. If this is another dry winter, managers for the Southland's biggest water agency say they will have to cut deliveries to local districts, leading to rationing.
Agriculture interests have called for the construction of reservoirs, water districts are urging homeowners to conserve water and environmentalists say it's time to recognize the limits of California's water supply.
"We need to make a fundamental change in how we see and use water," said Doug Obegi, an attorney with the Natural Resources Defense Council, one of the groups that filed the smelt lawsuit. "There are a ton more opportunities in water conservation, improved groundwater management, water recycling and design that captures storm water."
The pumping limits are also increasing pressure to build a canal that would skirt the ailing delta, taking water directly from the Sacramento River to the pumps.