SACRAMENTO — California Gov. Jerry Brown signed legislation Monday 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 one in the United States.
The measure implements several recommendations from experts who reviewed the crisis at Oroville Dam last year.
It requires annual inspections for dams deemed to be high hazards, 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.
The measure, AB1270, which passed the Assembly and Senate unanimously, 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 an eroding hillside would cause the uncontrolled release of a millions of gallons of water. The crisis was averted.
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.