Fresno Bee Newsroom Blog

Irrigation vapor from Central Valley gives Colorado River big bump

Massive water vapor from farm irrigation in California’s Central Valley each year blows over the Sierra Nevada, pumps up rainfall over other states and adds 100 billion gallons of water to the Colorado River, new research shows.

The Colorado gets nearly a 30% bump in stream flow. That’s enough water to fill nearly two-thirds of Millerton Lake near Fresno.

The study, led by climate hydrologist Jay Famiglietti of the University of California at Irvine,  will be published Tuesday in the journal Geophysical Research Letters. This part of the water cycle has not been accurately described before, Famiglietti said.

If irrigation stopped in the Central Valley, there would be a decrease in the stream flow of the Colorado River basin — a supply of water that has been hotly contested for decades.

The Colorado River basin provides water to Los Angeles, Las Vegas, Phoenix and other cities. Nearly 35 million people, as well as more than 3 million acres of farmland, rely on the water.

The study says more than 12 million acres of farmland are irrigated in the Central Valley, which includes the Sacramento and San Joaquin valleys. As water evaporates into the air, it is caught by the wind and taken over the Sierra.

As it moves into the interior of the Southwest, the vapor feeds into the annual monsoon cycle that includes moisture from the Gulf of Mexico, Famiglietti said.

“Adding the moisture from the Central Valley makes storms wetter and more violent,” he said. “It’s like throwing fuel on a fire.”

He said climate computer models make it possible to isolate the contribution from the Central Valley. The research is an effort to account for as many weather influences as possible.

Famiglietti’s study says about 40% of the irrigation in the Central Valley comes from ground-water pumping, and that worries him.

He wonders what it will mean to the Colorado River If land must be taken out of production as the ground water is depleted.

“It raises questions about the future,” he said.

Time to regulate underground water quality on farms

A dreaded time has arrived for some farmers in the San Joaquin Valley — enforcement of the state’s new underground water quality regulations.

Thousands of farmers north of the San Joaquin River will be the first in the Valley to experience it. Farmers on 1.1 million acres in Madera, Merced and Stanislaus counties are being told to sign up for it.

This campaign does not yet include farmers in Fresno, Tulare, Kings and Kern counties, but the enforcement will come to their land in the next year or so, according to the state.

The program is necessary, say environmentalists and activists for rural towns with drinking water wells in farm country. They say water needs to be protected fertilizers, pesticides and other possible threats.

Rural Valley towns have some of the most fouled water in the state.

Farmers fear extra costs of this new program. They’ve had a decade to worry about it as the Central Valley Regional Water Quality Board prepared the rules and enforcement.

To help farmers, ease the cost and organize the regulation, state leaders have allowed coalitions to represent broad areas. The East San Joaquin Water Quality Coalition will represent the Madera, Merced and Stanislaus counties, according to the regional board.

The coalition has about 2,500 members, but there are several thousand more farmers who are not part of the group yet. If they sign up by May 14, their costs will be $50 for annual dues and a $4 per acre for water sampling and expertise in the paperwork the state requires.

The costs probably will be different for other coalitions in the Valley, depending on the need for monitoring, evaluation and cleanup.

But farmers who go it alone without coalitions will pay more, state leaders say. On their own, farmers will have to get individual permits from the state and pay for their own consultants to do the work.

For more information about the East San Joaquin Water Quality Coalition, call (209) 522-7278 or go to www.esjcoalition.org.