FRESNO -- Politicians and water officials reacted with dismay to water cuts announced Friday by the U.S. Bureau of Reclamation.

The reduced allocation drew an outcry not only from the Westlands Water District, which includes about 600,000 acres on the Valley's west side, but also from members of California's congressional delegation.

"The water supply reductions facing farmers will devastate the local communities," said Thomas Birmingham, Westlands' general manager.

"We understand that the most recent cut imposed by Reclamation is the result of record dry conditions ... but this reduction is being imposed after the loss of hundreds of thousands of acre-feet of water during a record wet December."

Birmingham said that when water was plentiful, pumping from the delta was restricted by federal environmental decisions protecting the delta smelt, a small fish.

"This lost water would have enabled 100,000 acres of agricultural land to be put into production," he said. "Instead, farmers in Westlands will lose $350 million in revenue."

Federal officials said Friday that the past couple of months of dry weather had prompted a decrease in water allocations to contractors south of the Sacramento-San Joaquin river delta to 20% of the contracted supply. In February, the bureau had estimated the allocation at 25%. This cut will affect primarily the west branch of the Central Valley Project, as the federal project is known. Only one Kern County water district relies on that side of the CVP, the Kern Tulare Water District.

"It hurts bad," Kern Tulare's general manager Steve Dalke said of going down to 20%. His district contracts for 50,000 acre feet of water a year from the CVP. It's annual demand is about 40,000 acre feet, he said.

Going down to only 10,000 acre feet will mean his farmers will have to pump a lot more ground water. And they'll be puming out of the Rosedale area which has already had residential wells go dry in recent years from excessive groundwater pumping.

"It's a tough shortage especially when you consider all the Northern California reservoirs are at average," he said. "The only one that's low is San Luis and that's because they're not able to pump south of the delta because of the smelt."

Several water districts had complained that state and federal officials periodically stopped pumping this winter and let 800,000 acre feet flow out to the ocean in order to protect the endangered delta smelt fish, which had been pushed closer to the pumps by heavy rains in November and December.

Dalke said that makes this new cut, which is based on dry weather, even more painful to bear.

The only other CVP contractor in Kern is the Arvin-Edison Water Storage District. But it gets its water from the Friant-Kern division on the east side of the valley, which starts at Millerton Lake, said Arvin-Edison General Manager Steve Collup.

Water delivery for the east side is estimated to be slightly better than last year at about 65 percent, he said.

The earlier allocation for the west branch of the CVP was based on pumping restrictions in the delta to protect threatened fish species under the federal Endangered Species Act.

But dry weather from January through March prompted federal officials to classify the Sacramento and San Joaquin river supplies as critical based on reduced river flows into the delta.

The reduction means that farm water contractors in the Valley can expect to receive less than 400,000 acre-feet of water from their contracted supply of under 2 million acre-feet. An acre-foot is about 326,000 gallons, or the volume of water it takes to cover an acre of land under 12 inches of water.

Rep. Jim Costa, D-Fresno, said the reduced allocation "is like changing the rules for a game after the first quarter of play."

Costa said this was the first time in five years that the Bureau of Reclamation has sliced the water allotment from its original forecast.

"Simply put, the [Obama] administration is headed in the wrong direction on this one," Costa added. "They must use every ounce of flexibility available to keep water flowing to our Valley. A 25% allocation was unacceptable, but 20% is simply devastating."

Sen. Dianne Feinstein, D-San Francisco, described the reduction as "a crippling blow to California's farm community."

Feinstein said that in 2010, another dry year, the various partners in the Central Valley Project -- including the Interior Department, Bureau of Reclamation, the state and water contractors -- were able to work out an agreement to provide an extra 150,000 acre-feet.

"I encourage Interior and Reclamation to follow that same formula again this year," Feinstein said. "The water allocation must be increased if California farmers are going to be able to produce."

David Murillo, the bureau's Mid-Pacific Region director, said the agency is looking for ways to augment water supplies, including water transfers and exchange programs or other arrangements "that could lead to additional flows in the system."

Federal officials are "exploring all options to assist in alleviating the serious impacts of these drought conditions," Murillo said.

Water allocations for farming, environmental uses, cities and industries are calculated with a dizzying array of considerations, including water quality regulations, river flow goals, water rights and federal Endangered Species Act measures.

-- Reporting by Tim Sheehan of The Fresno Bee and Lois Henry of The Californian.