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Is Building A Reservoir Within A Reservoir The Answer To California's Long-Term Water Crisis?

Oct 7, 2014

It’s been one of the worst dry spells in recorded history in California and some rain would be nice. One possible answer to the state’s water woes could come as soon as November, when a new water bond goes before voters. To answer the state’s future water woes a water bond is on the November ballot which if passed could create new reservoirs.  FM89’s Ezra David Romero reports from Fresno County where planners are already studying the site for what could be the state’s newest water storage facility.  

The idea of a reservoir within a reservoir sounds sort of impossible, but in Fresno County that’s what water leaders want to build.  

Ron Jacobsma took me out on his speedboat to the site of the proposed dam.

"We're looking at more efficient ways to build Temperance Flat. You could construct this facility we've heard in about three years barring any major flood type of year." - Ron Jacobsma

It’s in the middle of Millerton Lake on the San Joaquin River.

“It would extend probably about four to five hundred feet above where we’re at on the water right now,” Jacobsma says. “Because about a hundred and fifty feet of it would be in the lake.”

Jacobsma is the general manager of the Friant Water Authority which represents 15,000 farmers on the east side of the San Joaquin Valley.

The idea of expanding Millerton Lake has been debated for decades, but come November, California voters have the option to approve a $7.5 billion water bond known as Proposition 1. A portion of the money could be used for Temperance Flat, adding a net 1.26 million-acre-feet of extra storage.

“You know if global warming materializes like they suggest we are going to get earlier inflow,” Jacobsma says. “And all those things just continue to help to emphasize why Temperance Flat is something we really need to explore.”

This is the proposed site of Temperance Flat.
Credit Ezra David Romero / Valley Public Radio

But the water bond alone won’t be enough to build Temperance Flat, which would be the first large reservoir, built in the western Sierra since the 70's. Up to half of the $2.6 billion reservoir could be covered by the water bond. Water users would pay for the rest. Even then, the dam would still need state and federal approval. It would also have to compete with other projects like Sites Reservoir northwest of Sacramento and ground water storage.  

“We’re looking at Sites, down scaling it a little bit,” Jacobsma says. “We’re looking at more efficient ways to build Temperance Flat. You could construct this facility we’ve heard in about three years barring any major flood type of year.”

"The water supply benefits of the dam are pretty low for a dam that's construction costs are estimated in excess of $2.5 billion. It's just a really poor water supply bang for the dollar." Jeffrey Michael

Temperance Flat would be built 6.8 miles up from Friant Dam, near the back of Millerton Lake and would flood two Pacific Gas & Electric Co. hydro power plants.

But not everyone is convinced the reservoir is a solution for the region’s water shortage. Ron Stork with the Sacramento-based advocacy group Friends of the River opposes Temperance Flat.

“This river has already been dammed and re-dammed and diverted,” Stork says. “No matter how much more concrete you want to pour in those river canyons you’ve already squeezed out nearly out all the water and you can’t squeeze out much more.”

He says the idea of a reservoir will eventually fade away because it’s not an efficient use of the bond.

“They’ll be a big political push but eventually they’ll run into the cruel reality that the projects are financially unfeasible and eventually they will die a quiet and unlamented death,” Stork says.

A lot of that push comes from Farmers like those Jacobsma represents.  However they say the environment would also benefit by boosting restoration efforts along the San Joaquin and reestablishing salmon runs.

“The ecological value to support a Salmon fishery that goes through the Delta is probably the biggest public benefit,” Jacobsma says.

By expanding Millerton Lake with Temperance Flat there would be a net 1.26 million-acre-feet of water storage added.
Credit Ezra David Romero / Valley Public Radio

But others like Jeffrey Michael an economist and professor at the University of the Pacific are skeptical.

“I don’t think it’s going to happen even with the water bond subsidy the  dam has got some financial and environmental challenges ahead of it that are going to be pretty significant obstacle,” Michael says.

"In 2010 and 2011 we had a million acre feet of flood releases, Temperance Flat's 1.3 million acre feet. That's water we could of captured if we'd of had it." - Ron Jacobsma

Jeffrey says the additional 75,000 acre- feet per year of water storage isn’t worth the cost.

“The water supply benefits of the dam are pretty low for a dam that’s construction costs are estimated in excess of $2.5 billion,” Michael says. “It’s just a really poor water supply bang for the dollar.”

Back on the lake Jacobsma says the new reservoir if ever built could very well fill in the need for water during dry years.

“In 2010 and 2011 we had a million acre feet of flood releases, Temperance Flat’s 1.3 million acre feet,” Jacobsma says. “That’s water we could of captured if we’d of had it.”

Groups will weigh in through a draft environmental study open through Oct. 21. But even if the water bond passes and Temperance Flat is granted funding it’ll take at least three years to build, which won’t answer the question of how the region will grapple with water issues until then.