Reflecting problems at other aging reservoirs, a $200 million project to drain and repair one of the Bay Area’s largest dams to reduce the risk of it collapsing in a major earthquake will double in cost and be delayed by at least two more years.

Managers at the Santa Clara Valley Water District, based in San Jose, had hoped to start construction in early 2018 on the seismic upgrade work at Anderson Dam, a 240-foot-high earthen dam that sits east of Highway 101 between San Jose and Morgan Hill.