California Reservoir on Shaky Ground Highlights Aging U.S. Dams' Risks

Jim Carlton on June 23, 2017

FREMONT, Calif. - The coastal mountains that frame this working-class city next to San Francisco Bay harbor a hidden menace: a reservoir 10 miles away that sits next to an active earthquake fault, which experts say could cause a dam break and flood thousands of homes.

The potential threat is so severe, the owner of the Calaveras Reservoir decided to build a replacement dam. But seven years after that work began, the dam is unfinished and isn’t expected to be complete until 2019—four years behind schedule.

The myriad issues hampering the Calaveras Reservoir project show how difficult it can be to repair or replace an old dam, which is of growing concern nationally.

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