A new earthquake retrofit project will render Santa Clara County’s largest drinking water source out of service for the next decade.
Amid a massive drought that’s forced local officials to impose 15% water use reductions, the Santa Clara Valley Water District held a ceremonial groundbreaking on its latest project Wednesday—a large outlet tunnel at Anderson Dam in Morgan Hill.
The tunnel, which will span 1,700 feet and be built next to the existing dam, will help release more water from the area during storms or emergencies.
The tunnel project is the first phase of the larger Anderson Dam Seismic Retrofit Project to strengthen the dam in preparation for the next large earthquake. After the tunnel is complete, Valley Water will reconstruct some of the dam’s embankments to make it sturdier.
The rest of the retrofit project is set to break ground in 2024—when the tunnel is expected to be completed—and wrap up in 2031.
Current estimates put the project’s total cost at approximately $616 million, or $648 million with inflation. The tunnel portion of the project is estimated to cost about $162 million.
Once complete, the Santa Clara Valley Water District, otherwise known as Valley Water, hopes to fill Anderson Dam to full capacity again. The reservoir is currently at about 3% of its approximately 90,000 acre-feet capacity.
“This project brings us our water supply back once we get this project built,” said Valley Water CEO Rick Callender. “We’re going to get 90,000 acre-feet of water back in the valley. We need this project for our water supply.”
In 2011, Valley Water issued a report saying the dam was unstable and likely wouldn’t survive a strong earthquake. In response, the district pushed for Measure S in 2012, which helped fund approximately $65 million for the project.
The Federal Energy Regulatory Commission ordered Anderson Reservoir to be drained for public safety in February 2020. This means Santa Clara County’s largest drinking water reservoir will be unable to store water for the next 10 years during the project’s construction timeline.
Wednesday’s news conference drew elected officials like Reps. Zoe Lofgren and Ro Khanna and Assemblymember Ash Kalra.
Lofgren led quarterly meetings at the federal level to push for the project. According to research from her office, if an earthquake damages the dam while at full capacity, Morgan Hill will flood under 35 feet of water within 14 minutes.
“We’ve got a clean shot at fixing this (dam) so when the drought has passed, we will have the capacity for this storage facility,” Lofgren told San José Spotlight.
Anderson Dam was completed in 1950. The dam created the Anderson Reservoir in Coyote Creek east of Morgan Hill.
The retrofit comes during challenging times: Valley Water declared a water shortage emergency last month and set targets to reduce water use countywide by 15% of 2019 levels due to a statewide drought. Although the project may worsen water scarcity, officials say it’s critical to make sure the region can prepare itself for future droughts and other disasters.
“When you have more storage and you have more water supply, you can deal with a drought a little bit differently,” Callender said. “We’ll still have to do more. This is just part of the puzzle.”
In response to construction and the drought, Valley Water asks that residents limit watering lawns to three days a week and fewer at-home car washes without shutoff-nozzle hoses. Restaurants are advised not to give out glasses of water unless customers ask for them, and officials urge against filling or refilling swimming pools.
More than 20 miles north of the reservoir, the project has special meaning for those in South and East San Jose. More than 14,000 people were displaced by floods in those parts of the city in February 2017.
“I have residents from Rock Springs who are still displaced that have not come back because of the flood,” said San Jose Councilmember Maya Esparza, whose district includes Rock Springs.
Esparza added that she is impressed with the coordination between Valley Water and the state and federal governments on the Anderson Dam project.
“This project is critical to saving human life,” she said.
Editor’s Note: Rick Callender serves on San José Spotlight’s Board of Directors.