California

Governor Signs Dam Safety Bill a Year After Near-Disaster in Oroville

A spillway at the nation's tallest dam showed signs of erosion in February 2017, prompting evacuations and legislation

California Gov. Jerry Brown has signed legislation that seeks to beef up dam inspections following a near-disaster that caused the evacuation of almost 200,000 people living downstream from the tallest U.S. dam.

The measure signed Monday implements several recommendations from experts who reviewed the crisis at Oroville Dam last year.

It sets standards for inspections and requires periodic review of dams' original design and construction records. It also requires inspectors to consult periodically with independent experts and makes inspection reports public.

AB1270 was written by Assemblyman James Gallagher of Yuba City, who was among the people forced to flee when both the main and emergency spillways experienced catastrophic damage. Engineers feared the uncontrolled release of a millions of gallons of water.

The crisis was averted during what turned out to be one of the wettest winters on record in California. 

Independent experts said Department of Water Resources officials mistakenly believed for years that the spillways sat on solid bedrock, even though reports from geologists and construction crews planning and building the structure reported significant erodible soil.

The annual inspections would be required for dams classified as being significant, high or extremely high hazards, and every two years for dams classified as low hazard. Critical spillway control features would be tested each year and witnessed by state inspectors at least every three years.

The federal rankings are based on factors including the size of the dam and its degree of risk to people downstream, not the dam's current condition.

Copyright AP - Associated Press
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