A new earthquake retrofit project will take Santa Clara County, California’s largest drinking water source out of service for the next decade.
The Santa Clara Valley Water District held a ceremonial groundbreaking on its project July 7, a large outlet tunnel at Anderson Dam in Morgan Hill, reported The San Jose Spotlight. Local officials have already imposed 15% water use reductions due to extreme drought conditions.
The project will require Anderson Reservoir to be drained, rendering it unusable for 10 years, reported KTVU Fox 2 News.
According to the Santa Clara Valley Water District, otherwise known as Valley Water, Anderson Reservoir is currently limited to about 3% of its capacity due to earthquake concerns.
This project will consist of earthquake retrofitting of the Anderson Dam to improve reliability, safety, and return the reservoir to its original storage capacity, reported The San Jose Spotlight.
“This project brings us our water supply back once we get this project built,” said Valley Water CEO Rick Callender, reported The San Jose Spotlight. “We’re going to get 90,000 acre-feet of water back in the valley. We need this project for our water supply.”
The tunnel will span 1,700 feet and be built next to the existing dam, with the goals of releasing more water from the area during storm events or emergencies.
This is the first phase of the larger Anderson Dam Seismic Retrofit Project to strengthen the dam to prepare for future earthquakes. Once the tunnel is complete, some of the dam’s embankments will be reconstructed as well, according to The San Jose Spotlight.
The rest of the project is set to break ground in 2024 and then finish in 2031.
According to estimates, the project’s total cost is approximately $616 million ($648 million with inflation), with the tunnel portion of the project estimated to cost $162 million, reported The San Jose Spotlight.
The Federal Energy Regulatory Commission ordered Anderson Reservoir to be drained for public safety in February 2020, so the county's largest drinking water reservoir will be unable to store water for the next 10 years, reported Mercury News.
The project was voter approved as part of the Safe, Clean Water and Natural Flood Protection Program.
Valley Water is asking that residents limit watering lawns to three days a week and engage in fewer at-home car washes without shutoff-nozzle hoses, reported The San Jose Spotlight. Restaurants are also advised not to give out glasses of water unless customers ask, and officials are urging against filling or refilling swimming pools.
