San Luis Reservoir expansion in Merced County?

Posted by Mark Grossi on December 4, 2013 

San Luis Reservoir was near record low storage this year.


Federal authorities last week released a draft appraisal of enlarging San Luis Reservoir, the major watering hole in the center of the state. San Luis already had been hot news this year. Now it’s hotter.

The reservoir usually gets a spotlight each summer as west San Joaquin Valley farms and Southern Californians call for more water. A lot of their water comes through San Luis, one big example of how California has radically replumbed nature.

The 2 million acre-foot reservoir has no natural stream to fill it. The water is pumped from Northern California rivers.

Drought and environmental pumping restrictions have kept the reservoir level to near-record lows this past summer, much to the dismay of farmers and cityfolk. Their worries have made a lot of headlines this year.

Talk of reservoir expansion raises hopes that more water can be sent to this watering hole when there’s a big winter. And that moves the discussion into the perennial fight over restoring the troubled Northern California water system that supplies the water.

I’m not going there today. Let’s stay with San Luis Reservoir expansion instead.

The reservoir’s earthen dam, 12 miles west of Los Banos, could be raised 20 feet to expand the reservoir by about 130,000 acre-feet of water, says the draft federal appraisal.

That’s about a 6% increase in capacity, and the estimated cost is $360 million. But water supply isn’t the only reason this appraisal was done, says the U.S. Bureau of Reclamation.

The enlargement also would allow the federal government to shore up the dam and reduce earthquake risk — the Ortigalita fault crosses beneath the reservoir.

Expanding the reservoir also would help prevent algae blooms that affect water quality for city water users in the Santa Clara Valley Water District, according to the bureau.

This is not a new idea. It has been kicked around for many years. And this appraisal report is a far cry from being a construction project.

Keep your eye on it though. California faces a possible third dry year in a row this winter.

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