Oroville Dam spillway repair continues as crews install rebar in phase 2 of the project
California water officials have always insisted public safety was their only concern as they struggled with the crisis unfolding last February at Oroville Dam.
The forensic team investigating what happened at Lake Oroville, however, has pinpointed another factor guiding the decisions made by the Department of Water Resources: the state’s desire to continue shipping water to faraway farms and cities that rely on deliveries from the reservoir.
DWR officials faced a difficult choice after a giant crater formed in Oroville Dam’s main flood-control spillway during a heavy rainstorm Feb. 7. Should they dump huge volumes of water over the badly damaged spillway, in order to keep reservoir levels low? Or should they minimize water releases over the spillway in order to limit the damage, even if that meant the lake would fill up and water might flow over the dam’s adjacent emergency spillway, which had never been used?
Ultimately DWR chose to limit the water releases over the main spillway – a decision that would trigger the chaotic two-day evacuation of 188,000 people. At the time, DWR officials said this approach would maximize their ability to control water levels in the reservoir during the rest of the rainy season.
What they didn’t say – according to the forensic report – was that this decision would also preserve their ability to deliver water through spring and summer to the agricultural and urban water districts as far away as San Diego that belong to the State Water Project.
How important was that? One top official at DWR told the forensic investigators that losing the ability to deliver water “was deemed as potentially one of the biggest disasters in the history of California,” according to the investigators’ final report. The forensic team declined to identify the official.
State officials said keeping downstream residents safe was their only concern and any suggestion otherwise is “absolutely not accurate,” said Joel Ledesma, deputy director of the State Water Project, who was a member of the spillway incident command team.
“Water delivery was never a conversation any of us had at any point in time,” Ledesma said in an interview Tuesday. He said every decision to regulate flows from the lake during the crisis was vetted by a team of DWR officials and federal dam safety regulators with public safety as the sole focus.
In any event, the forensic team said DWR’s choices proved problematic. With water releases curtailed over the main spillway, lake levels rose and eventually overtopped the emergency spillway – a concrete lip atop an unlined hillside. As the water chewed away the hillside, threatening the integrity of the structure, officials ordered the frantic evacuation of people living downstream of the dam.
In a 584-page report released Jan. 5, the forensic team hired by the state to investigate the Oroville debacle blamed faulty design work and shoddy maintenance for the initial failure at the main spillway. The team also criticized the DWR for putting too much priority on the “water delivery needs” of its customers to the south, while neglecting its dam-safety program.
The team also took aim, in a 21-page appendix tucked near the back of the report, at the decisions made by DWR officials during the hectic early days of the crisis.
The forensic report said DWR officials made crucial missteps in the days leading up to the evacuation. They essentially dismissed warnings from geologists that water flows “might undermine the emergency spillway,” according to the report. Then they misinterpreted hydrological models about the volume of water that could pour over the emergency structure, and came to believe the flows “would be minimal,” the report said.
John France, a Denver engineering consultant and leader of the forensic team, said his group was trying to offer insights for future crises instead of second-guessing DWR officials. “Being in those situations, it’s really hard, you’re getting a lot of mixed information from a lot of different people and they’re seeing it from their world and their perspective,” he said in an interview Monday.
The report said the engineers and others advising Bill Croyle, who was then acting director of DWR, fell into two main camps. The geologists “were adamant that the risks of using the emergency spillway should trump all else.” The other group, those with electrical and mechanical backgrounds, felt it was important to limit water releases over the main spillway in an effort to keep the crater from expanding, possibly up to the top of the structure, crippling the spillways’ main gates.
Croyle, who has retired, didn’t return a message left at his home. DWR spokeswoman Erin Mellon said Croyle and his team were trying desperately to find “a sweet spot” of releases down the main spillway keep the lake from spilling while also preventing critical infrastructure used to drain the lake from getting wiped out.
“Without (the power plant) and with a broken spillway, you have no way of releasing water in a controlled manner,” Mellon said.
If the crater grew, tons of additional debris would fall into the Feather River below. The debris would clog the channel, back up the water, and possibly flood the dam’s hydroelectric power plant, putting it out of operation for weeks if not months.
For top DWR officials, keeping the power plant intact was a major concern. For one thing, the plant could release up to 14,000 cubic feet of water per second – a vital tool for reducing lake levels. If the power plant were inoperable, DWR would have to use one or both spillways to keep lake levels in check during the spring, delaying the start of the reconstruction work, according to the forensic report.
The powerhouse had another benefit: Once the lake level drops below a certain point, it’s the main vehicle for releasing water for delivery to State Water Project member agencies, such as the Kern County Water Agency and the Metropolitan Water District of Southern California. It also is needed to release water to maintain water quality throughout the watershed and into the Delta.
If the powerhouse got flooded, “there would be limited downstream water availability in the coming summer,” the forensic report said.
“It’s certainly a fair statement to say they were concerned about (water deliveries), and it was one of the significant factors they were considering in that decision,” France said in the interview Monday.
The forensic investigations said the decision to make the power plant a high priority was flawed. First off, dam operators overestimated the risk that the plant was going to be flooded, the investigators said.
And even if the power plant had flooded, the state’s water supply wouldn’t have been crippled, the forensic report said. The winter was becoming so wet, downstream water agencies could have withstood a summer of curtailed water deliveries from Oroville. The forensic team dismissed the unidentified DWR official’s fear that major disaster would result.
“Rather than being portrayed as potentially one of the biggest disasters in history, the reduction in water availability to downstream contractors would have perhaps been more correctly portrayed as presenting significant business and legal challenges,” the investigators wrote. “Actual reductions in water deliveries would have been no worse than in the drought years.”
Outside experts said it’s no surprise DWR was concerned about maintaining State Water Project deliveries.
“They’re always worried about it; that’s why the thing was built in the first place,” said Jeffrey Mount, a geologist and water-policy expert at the Public Policy Institute of California. “People tend to lose sight of that.”
Mount added that “the entire decision to build the dam was built around the State Water Project....It created ancillary flood control benefits downstream, but its primary purpose was the State Water Project.”
Oroville-area elected officials and community leaders say this focus on shipping water adds to their frustrations. They’ve long argued that the safety and well being of locals who live in the shadow of the dam is a secondary priority to the DWR.
“It just confirms (residents’) mistrust of the department, and it will elicit even more anger,” said state Sen. Jim Nielsen, R-Tehama. “It makes the hill for the Department of Water Resources a lot higher to climb before people will trust that department. They’ll say, ‘You don’t give a dang about us. What about us? What about the 188,000 of us who had to evacuate our homes?’”