LOS BANOS — A $100 million project that will raise the B.F. Sisk Dam at San Luis Reservoir by 10 feet will add another 130,000 acre feet of critical off-stream water storage broke ground Friday.
Increasing the dam to 392 feet will also involve seismic retrofitting.
It will bring overall capacity to 2,171,000 acre feet.
Even though the Bureau of Reclamation reservoir is south of the Delta, the increased storage it will provide will benefit water users elsewhere by being able to hold more excess winter runoff that is now flowing into the San Francisco Bay.
Climate models anticipate more water flows into the Delta during the winter due to the expectation of warmer rains in the higher Sierra changing snowmelt patterns.
San Luis is already the largest off-stream reservoir in the United States.
Water is diverted from the California Aqueduct during heavy flow periods and stored there until needed by area farmers as well as agricultural and urban users farther south.
The reservoir also supplies water for 60,500 acres in the Santa Clara Valley.
On Monday, San Luis Reservoir was at 41 percent of capacity with 837,026 acre feet. That is 69 percent of the historic normal for June 20.
It is not unusual for the reservoir to drop close to 15 percent capacity as the water years unfolds and its stored water is released into the California Aqueduct.
“If we’re going to find more water for California — for the environment, for farmers, for people to drink — we’ve got to have a lot more projects like this,” noted Assemblyman Adam Gray, noting that while the reservoir is in his district, it benefits Californians from San Diego to San Francisco as an integral part of the state’s water system.”
The lack of data and faulty modeling tools has been especially frustrating for Gray, who has asked for an audit of the Department of Water Resources after it overestimated the 2021 Sierra runoff and released 625,000-acre feet in anticipation of runoff that never arrived. That water could have supplied every household in the Bay Area for a year with enough left for Fresno and Modesto.
“We’ve got a broken system,” said Gray. “All of the talk about conservation and efficiency, those are short-term solutions. What about the long term? How do we have water security for our state’s future? That’s what we must figure out.”
Tom Birmingham, general manager of Westlands Water District, noted that a very wet 2019 left both the federal Central Valley Project and State Water Project reservoirs virtually full. But only two years later, farmers got zero allocations after most of the water once in storage went to environmental uses.
“We fallowed 267,000 acres in Westlands alone,” said Birmingham. “The point is, that two years after one of the wettest years on record, the CVP couldn’t supply any water for (South Valley) contractors.”
“California is at a crossroads,” said Federico Barajas of the San Luis Delta Mendota Water Authority, which relies on water from San Luis Reservoir. “We’re facing the impacts of climate change — having this horrible drought just two years after having the wettest year on record.”
To contact Dennis Wyatt, email dwyatt@mantecabulletin.com
