U.S. dam safety frameworks have helped to prevent major calamities, but the May collapse of the 95-year-old Edenville Dam in Michigan illustrates that key failure risks remain—often involving many causes, according to a study of dam safety risk assessments by Oak Ridge National Laboratory.
In an effort to move forward a $576 million Anderson Dam Seismic Retrofit Project, the California State Assembly passed AB 3005 on June 8, the Expedited Dam Safety for Silicon Valley Act, facilitating the construction of the project.
Assemblyman Robert Rivas (D-Hollister, Calif.), who wrote the bill, says the overwhelming vote of bipartisan support shows the importance in fixing the dam. “The clock is ticking on a catastrophic dam failure in case of a large earthquake,” he says, “and we can’t allow bureaucratic delay to increase risks to public safety, water security and environmental protections.”
Three months after federal dam safety regulators ordered Anderson Reservoir, the largest reservoir in Santa Clara County, to be drained due to earthquake concerns, new details are emerging on what will happen to all that water, the fish that depend on it, and the water supply for Silicon Valley.
The Santa Clara Valley Water District, which owns the 7-mile-long reservoir located east of Highway 101 between Morgan Hill and San Jose, has drawn up plans to begin emptying it starting Oct. 1.
More than 15,000 dams in the US would likely kill people if they failed, and at least 2,300 of them are in poor or unsatisfactory condition, according to recent data from the federal government’s National Inventory of Dams.
In a dramatic decision that could significantly impact Silicon Valley’s water supply, federal dam regulators have ordered Anderson Reservoir, the largest reservoir in Santa Clara County, to be completely drained starting Oct. 1.
The 240-foot earthen dam, built in 1950 and located east of Highway 101 between Morgan Hill and San Jose, poses too great of a risk of collapse during a major earthquake, the Federal Energy Regulatory Commission, which regulates dams, has concluded.
“It is unacceptable to maintain the reservoir at an elevation higher than necessary when it can be reduced, thereby decreasing the risk to public safety and the large population downstream of Anderson Dam,” wrote David Capka, director of FERC’s Division of Dam Safety and Inspections, in a letter to the Santa Clara Valley Water District on Thursday.
U.S. Sen. Kirsten Gillibrand on Tuesday called for more federal money and oversight to shore up the nation’s aging dams following an Associated Press investigation that found scores of potentially troubling dams located near homes and communities across the country.
A climate-driven shift toward extreme storms has compelled Colorado officials to rethink the safety of hundreds of dams across the state that hold water and mine waste, including 27 high-hazard structures near people that already are listed as deficient.
They’re trying to calculate the potential for sudden hard rain resulting in flooding and accelerated erosion that could trigger fatal collapses.
It is a telling illustration of the precarious state of United States dams that the near-collapse in February 2017 of Oroville Dam, the nation’s tallest, occurred in California, considered one of the nation’s leading states in dam safety management.
The Oroville incident forced the evacuation of nearly 190,000 people and cost the state $1.1 billion in repairs. It took its place as a seminal event in the history of U.S. dam safety, ranking just below the failures in the 1970s of two dams.
The Water News Network is San Diego County’s source for water news and information.
