After years of underwhelming winter storms, 2017’s abundant rain has been a mostly welcome sight for California’s water-starved communities. However, the respite from years of drought has exposed a vulnerability shared by much of the United States: the poor state of its dams and water infrastructure.
On February 7, a pothole approximately 250 feet long and 30 feet deep appeared in the main spillway of Oroville Dam in Northern California. The dam is the tallest in the U.S. and contains the second-largest reservoir in California, but it is just one of tens of thousands of dams across the country that are nearing the end of their designated lifespan.
“By 2020, 70 percent of the total dams in the United States will be over 50 years old,” noted the American Society of Civil Engineers in their report card on the nation’s infrastructure. “Fifty years ago dams were built with the best engineering and construction standards of the time. However, as the scientific and engineering data have improved, many dams are not expected to safely withstand current predictions regarding large floods and earthquakes.”
The pothole threatened to erode the spillway structure at the dam, making it risky to release water from Lake Oroville during the intense recent storms. Without the spillway, engineers could not release enough water to keep up with the rain.
The result has been close to a worst-case scenario, with the dam’s emergency overflow being used for the first time in the structure’s 49-year history. Erosion at the emergency spillway site has resulted in a mandatory evacuation of nearly 200,000 people in the event the concrete weir fails, and the main spillway has been reopened despite the pothole.
“It was a tough call to make,” said Bill Croyle, acting director of the California Department of Water Resources, in a press conference about the evacuation and use of the damaged spillway. “It was the right call to make to protect the public.”
Oroville Dam is a centerpiece of the intricate water system that buoys California’s economy. The dam’s reservoir supplies California’s statewide water system, including the Los Angeles metropolitan area, and generates over 800 megawatts of hydroelectric power for the region.
While the outcome remains uncertain, the crisis in Oroville has already provided evidence that the way the country plans for and maintains its dam infrastructure is due for reform. The day after the mandatory evacuation, the San Jose Mercury News reported that three environmental groups had petitioned the Federal Energy Regulatory Commission (FERC) to require paving the emergency spillway as part of the dam’s re-licensing approval in 2006. They warned that the structure’s earthen drainage surface would not withstand a spillover, potentially compromising the structure.
This type of deficiency in the nation’s dams may be more common than the public believes. There are an estimated 2 million dams in the United States, many of which are obsolete and no longer serve their intended purpose. Nearly 4,000 of them are considered deficient and by 2020, more than 65 percent will be past their designated lifespan. Only around 6,000 dams are owned or regulated by the federal government, which means updating these structures and protecting the public is hard to coordinate.
A report released by the Center for American Progress last October highlighted a number of policy solutions for addressing these challenges and avoiding future crises, including a federal Safe Dams Fund that provides matching funds for state dam safety offices to conduct maintenance, and a more thorough review of safety measures during federal re-licensing of hydroelectric dams.
On Tuesday evening, President Donald Trump approved requests from California Gov. Jerry Brown (D) and Rep. Doug LaMalfa (R), the area’s congressional representative, for federal emergency disaster funding to support relief efforts.