Water & Drought

Oroville Dam’s flood-control manual hasn’t been updated for half a century

The critical document that determines how much space should be left in Lake Oroville for flood control during the rainy season hasn’t been updated since 1970, and it uses climatological data and runoff projections so old they don’t account for two of the biggest floods ever to strike the region.

Independent experts familiar with the flood-control manual at Oroville Dam said Wednesday there’s no indication the 47-year-old document contributed to the ongoing crisis involving the dam’s ailing spillways. The current troubles stem from structural failures, not how the lake’s flood-storage space was being managed.

But the experts say Oroville’s manual does point to larger operational issues that affect most of California’s primary flood-control dams. Like the dams, most of the manuals were designed decades ago by engineers using slide rules instead of computers. Many of the documents and licenses that govern dam operations don’t account for advances in hydrology, meteorology and engineering, or for a changing climate.

“California’s flood infrastructure is based on the hydrology of the past,” said Jeffrey Mount, a senior fellow at the Water Policy Center at the Public Policy Institute of California. “They use the hydrology of the past to design the infrastructure of the future.

“I don’t know a scientist anymore who thinks the future is going to look anything like the past.”

The flood-control manuals are created by the U.S. Army Corps of Engineers. California has more than 1,500 dams, 54 of which are considered primary flood-control structures. The owners of those 54 dams – they include the federal government, the state and in some cases local water districts – must abide by the modeling outlined in the manuals during the rainy season. The modeling is designed to ensure there’s ample space in the reservoirs to capture heavy river flows and mountain runoff, and to prevent catastrophic flooding downstream.

The majority of the manuals haven’t been updated since at least the 1980s. Some are so old, their pages include charts drawn by hand in pen.

The California Department of Water Resources, which operates Oroville Dam, is required to make releases according to charts outlined in the dam’s manual. It’s dated August 1970, two years after the dam’s construction was completed.

Ann Willis, a researcher at the UC Davis Center for Watershed Sciences, is among the critics who say the the manuals are too rigidly tied to outdated weather models. At Oroville, the manual cites weather patterns prior to the 1950s, and data doesn’t account for the catastrophic floods of 1986 and 1997. Plus, the manuals are designed around weather patterns that include capturing water from spring snowmelt, an annual occurrence expected to shift, in both timing and amount, with continued climate change.

Army Corps officials say the manuals have done their jobs, despite their age.

“Just because a water-control manual is old doesn’t mean it’s obsolete,” said Joe Forbis, chief of water management at the Corps’ Sacramento office. “It still allows the reservoir to be operated appropriately.”

He acknowledged his agency would prefer to have updated manuals. But, he said, it’s difficult because the updates require complex engineering and environmental studies. Funding would have to be approved by Congress.

Most recently, the issue of outdated dam manuals came up in the context of California’s five-year drought. At Folsom Dam near Sacramento, local water agencies complained that federal dam operators were releasing too much water from the reservoir during a lengthy dry spell when no major storms were forecast and the state was trying to conserve water. Federal operators said they had no choice, because Folsom’s manual dictated that it create flood-control space based on the time of year.

Unlike many dams, Folsom will get an update to its manual as part of a $900 million installation of a new auxiliary spillway scheduled to be completed later this year.

Mount, of the Public Policy Institute, said dam operations are generally guided by rigid sets of rules that don’t allow for necessary operational flexibility.

“Adjusting course on dams – whether by changing the infrastructure or the way they are operated – is difficult,” Mount wrote in a post on the PPIC’s website Wednesday. “Licenses for non-federal dams like Oroville – administered by the Federal Energy Regulatory Commission – last for 30-50 years. These lock in place all aspects of dam operation for several generations and require herculean efforts to overcome.”

Butte and Plumas counties raise similar concerns as part of a lawsuit pending in California’s 3rd District Court of Appeal. The suit, filed in 2008, argues that another document critical to operations at Oroville Dam fails to reflect modern climate science.

In 2008, the Department of Water Resources conducted an environmental review of dam operations as part of the structure’s 50-year relicensing process. Plumas and Butte counties – whose communities sit in the Feather River watershed above and below the dam – sued, alleging the analysis was inadequate because it did not properly account for climate change.

“They called it ‘speculation,’ ” Butte County Counsel Bruce Alpert said Wednesday.

The case eventually was moved to Yolo Superior Court, and in 2012 Judge Daniel P. Maguire ruled in favor of the state. He echoed arguments made by Department of Water Resources lawyers when he wrote in his statement of decision that an environmental review “need not (and should not) speculate about the future.”

“It is a long step from the relatively generalized climate change data in the record to the project-specific forecasting demanded here,” the judge wrote, “and Petitioners have not carried their burden of showing that DWR could have taken this step.”

The counties appealed, saying the review relied on outdated forecasting models that “fail to protect the public against the hazards of more severe flood events or water supply shortages under climate change.” They are asking the higher court to direct the Yolo judge to set aside DWR’s certification of the environmental review.

DWR lawyers countered in their opposition papers that the environmental report “adequately considers climate change ... based on the limited information available at the time the EIR was certified in 2008.”

“We absolutely account for climate change in all of our planning processes, and the impacts of climate change are integral to the California Water Action Plan,” department spokesman Doug Carlson said in an email.

Jay Lund, director of the Center for Watershed Sciences at UC Davis, said he expects the malfunctions now crippling Oroville Dam will prompt a review of operations and likely an update of its operating manual as part of any retrofit. It also may focus attention on other aging flood infrastructure in the state.

“One thing you learn from civil engineering is you have to have failures in order to make progress,” Lund said.

Ryan Sabalow: 916-321-1264, @ryansabalow

Related stories from Sacramento Bee