State officials say that it will take 30 to 45 days to repair damage detected this week at a key point in the state’s system for shipping water from the Delta to farms in the San Joaquin Valley and to cities from Silicon Valley to Los Angeles.
But the Department of Water Resources says the damage, involving extensive underwater erosion around a concrete intake structure at Clifton Court Forebay in eastern Contra Costa County, should not result in an interruption of water deliveries to any of its many farm and city customers.
The forebay is a small reservoir that holds water to be pumped from the State Water Project’s pumps into the California and South Bay aqueducts.
The problem grows indirectly out of California’s extraordinarily wet winter and resulting high flows down the Sacramento and San Joaquin rivers into the Delta.
The State Water Project took the opportunity to run its Delta pumps full bore for weeks on end to ship water south. The resulting high flows are believed to have contributed to erosion around the concrete apron at the intake gates at the reservoir’s southeastern corner.
“What this erosion has done is undercut the apron where water flows across,” said Doug Carlson, a DWR spokesman. “We’re going to be putting concrete into the area that’s eroded over the next 30 to 45 days, hardening that and improving the apron.”
That work won’t begin until Thursday at the earliest, when the intake is completely shut down.
Carlson said because the State Water Project’s reservoirs are close to full and demand for water is low because of the season’s abundant rain, there should be no interruption of deliveries to the system’s customers.
San Luis Reservoir, shared by federal and state water projects, has reached its 2 million acre-foot capacity, in large part because of the aggressive earlier pumping.
“This is a perfect time to do this — if you had to pick a time, it would be now,” Carlson said. “You don’t like to have a problem like this, but when they do occur, it’s convenient that they occur when demand is low and we can get in there and get the job done without any interruption to scheduled deliveries.”
Carlson also said that deliveries would continue through the South Bay Aqueduct, which supplies parts of Alameda and Santa Clara counties.
The Clifton Court Forebay situation isn’t as dire as the public safety emergency that arose last month at the State Water Project’s Oroville Dam.
Damage to the dam’s main spillway led to water flowing over an emergency weir. The resulting erosion triggered concerns that the emergency structure would collapse and unleash a wall of water down the Feather River. Those concerns led to a mass evacuation from the town of Oroville and other downstream communities.
Construction crews continue to do short-term reinforcement of Oroville Dam’s spillway.