The Oroville Dam in northern California is the nation’s tallest dam and it creates the state’s second-largest reservoir. In February of 2017, an atmospheric river dumped a huge amount of snow then a huge amount of rain into the reservoir’s watershed.
A 30-foot wall at the top of the dam, called the weir, nearly gave way to the volumes of water and 188,000 people had to be evacuated.
Intensifying drought conditions in California and historically low water levels at the Oroville Dam on Aug. 5 forced the state’s Department of Water Resources to shut down the 644-MW Edward Hyatt Power Plant—the fourth-largest energy producer of all California’s hydroelectric facilities.
While the current drought is affecting 95% of the West, it is bearing down severely in California and in the Colorado River Basin. Multiple reservoirs monitored by the U.S. Bureau of Reclamation are “substantially” affected. The federal agency reported on Aug. 8 that at least six of its 44 major reclamation reservoirs—including Hoover Dam and Glen Canyon Dam—have now fallen to their lowest storage values in the last 30 years.
The drought is taking its toll on dams and rivers throughout California and there is no clearer example than at Lake Oroville where water levels have been dropping all year.
“It’s been dropping fast all year,” said fisherman Jeremiah Corlin. “It’s been slowing down, but it’s still dropping fast.”
The Oroville Dam is the state water system’s tallest, but boaters and fishermen have witnessed the water level fall nearly 250 feet below average.
The California Department of Water Resources has secured $308 million in funding to pay for reconstruction and repair work that has been done on the Oroville Dam’s spillways.
The funds, released by FEMA, are in addition to the $260 million that the agency provided for repairs on the lower portion of the dam’s main spillway.
The proposed federal spending bill for 2021 includes funding for the Oroville Dam, Sites Reservoir Project and new snow measurement technology. If passed by Congress, part of the massive omnibus spending bill would allocate $1 billion towards restoration projects and drought relief efforts.
It appears that repair work on the Oroville Dam’s damaged spillways has paid off.
A team of experts released their findings Monday, concluding that no urgent repairs are needed right now on the Oroville Dam. The report goes on to say that the largest earthen dam in America is safe to operate. However, the Oroville Dam is not completely in the clear.
There are no current risks to the Oroville Dam as the Potters Fire burns close by, according to the Department of Water Resources.
In a statement to KRCR, DWR says that they are working with CAL FIRE and local responders to protect critical infrastructure, like the high voltage transmission lines that provide generation to the California electrical grid. They add that their operations continue with essential staff on site.
Nearly 200,000 people were evacuated when the spillways failed at Oroville Dam in 2017, an infrastructure disaster that cost around a billion dollars to repair.
Three years later scientists say events that partially led to the incident could become more frequent. It comes down to how and when snow and rain fall.
This week, the California Department of Water Resources (DWR) will install eight new measurement devices at the base of the Oroville Dam. The devices, called piezometers will monitor seepage and will be used to confirm seepage measurements that the DWR already collects. Seepage refers to a small amount of water that can pass through the dam.
DWR said seepage is normal and expected, especially in large, earthen dams like Oroville. Seepage is measured and collected through a drainage system.
There were 56 piezometers originally installed in the dam fifty years ago which, as anticipated, have since stopped functioning. DWR plans to install additional piezometers throughout the facility in the coming years.
The vast majority of California’s major dams aren’t adequately prepared for an emergency.
Three years after the near-disaster at Oroville Dam, only 22 state-regulated dams have finalized emergency plans — out of 650 major dams that are required by law to have plans in place — according to a report issued Thursday by State Auditor Elaine Howle.
