West-siders hope for more irrigation water

12/27/2010 11:06 AM

12/27/2010 11:07 AM

Huge December storms and a federal court ruling have given west Valley farmers the best Christmas gift in years -- hope for more irrigation water next summer.

San Luis Reservoir on the west side is forecast to be full of Northern California water for the first time since 2006. West-side farm water supply next summer might be 55% of what growers want, a noticeable improvement from the 45% allotment this year.

The court decision -- rejecting parts of a protection plan for threatened fish -- gives water officials the chance to file legal action to keep Northern California pumps going if authorities order a slowdown this month for delta smelt.

But those developments don't give farmers what they really need: more water pumping from the Sacramento-San Joaquin Delta during spring and early summer. San Luis Reservoir does not hold nearly enough water for both state and federal customers, so it must be replenished with more delta pumping as the reservoir is drawn down in warmer weather.

Pumping cutbacks on the federal Central Valley Project -- up to 80% cutbacks in some months -- probably will continue in warmer weather to protect dying populations of smelt and salmon.

"Between now and June, there is still uncertainty for our water supply," said Dan Nelson, executive director of the San Luis & Delta-Mendota Water Authority, representing growers who irrigate 1.1 million acres of west-side land from Tracy to Kettleman City.

The largest customer is Westlands Water District, but there are 21 other similar farm customers on the west side. They face annual cutbacks in water supply even in wet years because water pumping has been linked to dwindling populations of delta fish.

Pumping restrictions coincide with fish movement, and the most critical months begin right now as smelt move through the delta to prepare for spawning.

Though part of the government protection plan for smelt has been rejected, the plan remains in effect until a remedy is determined. That process won't begin until early January in federal court.

Under the current plan, pumping could be curtailed over the next few days in response to turbidity or muddied water, which often occurs when there is a lot of flow.

Water officials could then ask a federal judge to temporarily ease the restrictions.

Turbidity in the delta is not bad for smelt, said ecologist Jon Rosenfield of the Bay Institute, an advocacy group in San Francisco. The fish can hide from predators in murky water.

But, if the turbidity draws the fish near the pumps in the south delta, they could be sucked in and killed.

West-side water officials say it's possible there's enough water in the delta this year to skip these early restrictions. But Rosenfield said federal wildlife officials need to be cautious.

He said the pumps have been damaging to smelt, salmon and many other kinds of fish.

"The conditions are better now than they were last year," Rosenfield said. "But we're talking about the delta smelt, a fish species that has lost more than 95% of its population. We need to protect them."

On Jan. 1, federal wildlife authorities are obligated to begin protections for another fish -- salmon. Water pumping will be curtailed based on flows going through two delta channels, known as Old River and Middle River. Both are tributaries to the San Joaquin River.

The water flow in Old and Middle rivers actually reverses and moves toward the federal and state pumping plants when the pumps are on. Biologists say migrating salmon can become confused and wind up swimming to their deaths at the pumps.

But in years when the San Joaquin is flowing higher -- as it is this year -- the problem is eased, said water resources engineer Tom Boardman, who works for the San Luis & Delta-Mendota group.

The San Joaquin feeds more water into the pumps, allowing the Sacramento River -- and the salmon -- to flow more toward the ocean, he said.

"With continued high flows in the San Joaquin, we might be able to hold pumping levels as they are right now at full capacity," Boardman said.

Long-range weather forecasts say winter rain and snow should remain above average for Northern California. But it might not make a big difference for west-siders.

In late February and early March, delta smelt begin to spawn. If they are discovered too close to the south delta pumps, wildlife authorities must again limit water exports to San Luis Reservoir.

From April 1 to the end of May, federal officials must trim water pumping by 80% for endangered salmon, unless the San Joaquin is still flowing high, water officials said.

But even if the San Joaquin runs higher in spring, the pumps can be ratcheted up only in small increments to make sure the salmon are protected.

In June, there are sometimes further cutbacks if smelt appear near the pumps. That means less water goes to San Luis Reservoir, which dips as the temperature spikes and farmers increase irrigation.

"The best we can do is try to keep the reservoir as high as possible for as long as possible," Nelson said.

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