An unprecedented shift of San Joaquin River water from farmers in the east Valley to those in the west could further complicate the scramble to save crops from drought this year.
At stake is precious San Joaquin River water, which has helped east-side farmers cultivate a multibillion-dollar economy on 1 million acres over the past half-century.
Many west-side irrigation districts import water from Northern California. But four of them also have historic rights to the river. Under terms of special contracts drafted decades ago but never exercised, the four could move to the front of the line for water from the San Joaquin.
The deal was made to free up enough river water for east-side farmers.
Facing drought and probable water-pumping restrictions in Northern California, federal authorities must decide whether they should tap Millerton Lake, where the river is held back by Friant Dam, for the west-siders.
On the east side, folks are uneasy. Nobody knows how much water could be lost.
"In the 50 years-plus of the project, there has never been a call like this on the San Joaquin River," said Ron Jacobsma, general manager of the Friant Water Users Authority, representing 15,000 east-side farmers.
During other dry years, officials have managed to avoid this step by providing more water from northern sources. But by next month there may be water-pumping restrictions in the Sacramento-San Joaquin River Delta to protect dwindling fish.
Reduced pumping means federal officials could not fill the San Luis Reservoir in western Merced County, where west-siders get their water. Even if the dry winter turns into a wet spring, the San Luis Reservoir would not get enough water to meet the irrigation demands, water officials fear.
"It's the regulatory issues driving this problem," said Steve Chedester, executive director of the San Joaquin River Exchange Contractors Authority, representing water users in the four west-side districts that agreed decades ago to exchange river water for a share of flows from the delta. "Drought you can deal with, but now you have limits to the amount of water you can bring south of the delta."
The exchange contractors include the Central California Irrigation District, Firebaugh Canal Water District, San Luis Canal Co. and Columbia Canal Co. Farmers in these districts grow garlic, tomatoes and other crops on 240,000 acres.
They are different from other federal contractors, such as Westlands Water District, which did not have historic rights to the San Joaquin River.
Under terms of the contracts in which they exchanged rights to river water, the districts receive water from the delta even in dry years when Westlands and others take big cuts.
But this year, even the exchange districts might have to take a 25% cut if the snowpack doesn't fatten up in Northern California.
With possible delta pumping restrictions, there may be only enough water in the San Luis Reservoir this summer to supply higher-priority customers, such as cities and wildlife refuges.
Westlands, Panoche, San Luis and other federal water districts could be completely denied federal water this summer. Federal officials, however, must find ways to get water for obligations under the exchange contracts, including possibly taking it from Millerton.
Bureau of Reclamation officials said they hope precipitation picks up significantly to satisfy water demands for all customers. Then, the Millerton option would not be necessary.
"But I think it's fair to say we're concerned about it now," said Michael Jackson, bureau area manager in Fresno.
The Millerton option almost happened in 1992, officials said. There were discussions between Friant and the exchange contractors to negotiate a compromise before federal officials were able to provide water from the north.
Said Chedester of the exchange contractor authority: "I remember Friant folks asking, 'What if we paid you to not irrigate alfalfa?' That was so they could save that water and not run it down the river to us. But we were rescued that year."