Pacheco Dam project moving forward
Water district board, while leery of rising costs, says it’s needed
Leaders of the largest water district in Silicon Valley decided Tuesday to move forward with a plan to build a $2.5 billion dam near Pacheco Pass in Southern Santa Clara County, in what would be the largest new reservoir in the Bay Area in 20 years despite learning that the cost has doubled due to unstable geology on the site.
Although several board members of the Santa Clara Valley Water District expressed concerns during their meeting about the growing price tag, others said the proposed project’s water storage is needed for the future, and that the agency should continue with studies and public meetings.
“This represents a very important part of the water supply system for the future,” said board member John Varela, who represents Gilroy and Morgan Hill, adding, “All of us should work toward completing this project, as long as it takes and how much it ever costs.”
The project, proposed by the Santa Clara Valley Water District, a government agency based in San Jose, calls for a 319-foot-high dam to be built along Pacheco Creek in the rural canyons just north of Highway 152 near Henry W. Coe State Park. For the past three years, the district has considered the dam to be a key part of the future water plans for 2 million people in the South Bay.
But studies by a contractor earlier this year found the area has unstable rock. About 130 test borings found that crews would have to dig down at least 30 feet deeper to hit bedrock than previously thought. That will add three years to construction — from five to eight years — and add least $1 billion or more in additional costs, water district engineers estimate, sending the price tag soaring from $1.3 billion to $2.5 billion.
Critics of the plan say that the price tag will make it difficult to find other Bay Area water agencies to partner with, and will raise water rates for Santa Clara County residents.
“There are a lot of alternative ways we can get this water, which would be less expensive, especially with this extreme cost escalation,” said Katja Irvin, water committee chair for the Si
erra Club’s Loma Prieta chapter.
She urged the board to pull the plug on the plan and instead expand conservation like boosting spending on rebates to pay people to remove lawns and install high- efficiency dishwashers, toilets and other appliances, and also to expand the use of recycled water. The Pacheco project, with the cost increases and geologic issues, she said, faces
the same fate as many other dams proposed over the years in California in difficult locations whose costs grew so high that the water’s price became impractical.
“It’s going to die of its own weight eventually,” Irvin said. “Hopefully sooner rather than later.”
The project, if it is ever built, would constr uct a reser voir that holds 140,000 acre feet of water — nearly as much as all 10 existing dams the water district currently operates. It would be the largest new reservoir built in the Bay
Area since 1998 when the Contra Costa Water District built Los Vaqueros Reservoir in eastern Contra Costa County.
Under the current plan, the water district would replace a small, existing dam and reservoir on the site near Highway 152 and build the Pacheco Dam about half a mile upstream.
The existing reservoir was built on the North Fork of Pacheco Creek in 1939. It can hold only 5,500 acrefeet of water behind an aging 100-foot-high earthen dam, while the new reservoir would hold more than
23 times as much. The district hopes to take water it now stores in nearby the massive San Luis Reservoir and pipe it into the new Pacheco reservoir, filling it during wet years.
The water district received a huge boost in 2018 when the administration of former Gov. Jerry Brown awarded it $ 485 million from Proposition 1 — a $7.5 billion water bond passed by voters in 2014. But to get that money, it must complete draft environmental studies by Dec. 31 and show how it will pay for most of the rest of the costs.
Board member Nai Hsueh said she is still “keeping an open mind,” but noted that $2.5 billion may not be the final price tag.
“The updated cost estimate will probably increase again,” said Hsueh, a civil engineer. “That’s the hurdle, the cost.”
The $2 billion or more the district needs to find for the project would almost certainly come from higher water rates, although the incoming Biden administration is proposing new spending on roads, bridges and water projects, which might provide some money.
The water district board also voted Tuesday to have its audit committee look into the timetable of how the price tag grew so fast, and why top officials at the agency weren’t notified earlier.
“There’s no question we are having a drought again,” said board member Dick Santos. “The best decision I can make is to keep this going. What do we do for our children and grandchildren for the future to have a source of water?”