Earth Log

May 19, 2014

Up to 40% losses expected in Friant Dam water releases

Earth Log

Mark Grossi's dispatches from the Valley battle with air quality and water use

Curious about the water flowing out of Friant Dam into the San Joaquin River during this intense drought? The news about it continues to evolve.

The headline last week was historic, as is this year's drought. 

On May 15, the federal government began a first-ever release of water meant for west San Joaquin Valley growers who have water rights dating back to the 1800s. Wildlife refuges also would get some water.

But that was last week. Today’s headline? Water will be lost in the process — 15% to 40% to evaporation and percolation into the dry Valley floor. The wide range is because weather conditions vary, federal officials said.

The U.S. Bureau of Reclamation, which owns and operates Friant Dam, did the math for me this week.

The flow will go until late August, sending out about 500 acre-feet per day — or about 200,000 acre-feet. With losses, 120,000 to 170,000 acre-feet of water will wind up at the Mendota Pool for use by some west-side farmers and refuges.

Bureau leaders said water soaking into the soil will help the underground water supply, which is good news for well owners in the area.

Others have called to remind me that landowners just below Friant Dam also will have a chance to divert some of that water. 

At the same time, other headlines haven't changed in many weeks. East Valley farmers, who would usually rely on the water behind Friant Dam, still will be shut out this year.


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About Mark Grossi


Mark Grossi has the pulse of the San Joaquin Valley ecosystem, writing since 1993 about subjects such as the region's notorious air quality, the restoration of the San Joaquin River and unhealthy drinking water in rural towns. Twitter: @markgrossi Email Mark at or call him at 559-441-6316.

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