Project to Drain Reservoir a Year Behind Schedule

The discovery of new “trace faults’’ near one of the San Francisco Bay area’s largest dams has further stalled a $193 million project to strengthen it.

📅   Tue February 23, 2016 - West Edition


The discovery of new “trace faults’’ near one of the San Francisco Bay area’s largest dams has further stalled a $193 million project to strengthen it.
The discovery of new “trace faults’’ near one of the San Francisco Bay area’s largest dams has further stalled a $193 million project to strengthen it.

SANTA CLARA, Calif. (AP) The discovery of new “trace faults' near one of the San Francisco Bay area's largest dams has further stalled a $193 million project to strengthen it, pushing back plans for a seismic retrofit to early 2018.

Plans to shore up the Anderson Reservoir in Santa Clara County were already a year behind schedule but the latest hitch surfaced when engineering crews found several “trace faults' not been known to exist, The San Jose Mercury News reported Nov. 28.

A few years ago state regulators ordered that the vast lake near Morgan Hill could not be filled any more than 68 percent full because geologic tests found that in a major earthquake, its 240-ft. (73 m) high earthen dam could slump, releasing a wall of water that could generate a trail of death and destruction all the way to San Jose.

Officials at the Santa Clara Valley Water District, which owns Anderson Reservoir, announced in November that instead of breaking ground in early 2017, they now hope to begin construction in early 2018. That means work won't be finished until 2021 or 2022.

“We have to get it right,' said Katherine Oven, deputy operating officer at the Santa Clara Valley Water District. “We want that dam to stay intact, operate and provide water supply for the next 50 years. We want to be well-informed of the potential seismic dangers.'

Still looming is when the water district will drain Anderson Lake to do the work. Oven said that will probably happen in the fall of 2017 and be done over a six-month period. District officials say more than half of Anderson's water will probably be sent to homes and businesses or pumped back into the ground to store in aquifers.

Gary Kremen, chairman of the water district's board, said, however, that if the drought drags into a fifth and sixth year, the water district may delay the draining because it will need every drop.

“Draining it during a drought is problematic,' he said. “You're damned if you do, damned if you don't. But it's got to be fixed.'