OROVILLE, Calif. — State water officials are sticking with their plan to lower Lake Oroville to below 700 feet in elevation this winter to accommodate reconstruction of the dam.
A flood operations plan for the winter and spring calls for the lake to be drawn down to 700 feet by Nov. 1 and for releases to continue thereafter so that crews can complete an underground cut-off wall for the emergency spillway by January, officials said.
The lake’s surface was at 701 feet on Oct. 18, compared to the average 780 feet elevation maintained in mid-autumn in previous years, according to the Department of Water Resources.
Releases will continue “at a much slower rate,” said John Leahigh, the State Water Project’s chief of water operations. But he said nature usually takes over in determining lake levels.
“If we continue to see dry conditions, we’ll see the lake be drafted down,” Leahigh told the Capital Press during a conference call with reporters. “As soon as we get some significant rains, the first several inches of rain is absorbed into soil. But at a certain point when we get enough rain, we’ll start to see inflows.”
The flood plan will allow for inflows up to a certain point, depending on the time of year, before the DWR boosts releases into the Feather River. For instance, if storms push the lake to 848.5 feet at any point during the winter, water will be released at the rate of up to 100,000 cubic feet per second to bring the surface down to 800 feet, according to the plan.
The plan is consistent with one the agency publicized last summer to lower the lake level to as low as 640 feet by Dec. 31, raising the eyebrows of Rep. Doug LaMalfa, R-Calif., whose district includes the Oroville area.
LaMalfa argued that draining the lake that low would only leave 850,000 acre-feet in the lake with only about 100 days left in the winter to fill it. The spillway gates aren’t touched by water until it reaches 813 feet, which is 2.35 million acre-feet of water, he said.
But the lower level will provide more than 2.2 million acre-feet of flood reserve storage to accommodate inflows during the rainy season and enable officials to keep lake levels well below 901 feet, the level that would require use of an emergency spillway that is still under construction, DWR spokeswoman Erin Mellon said.
Lake Oroville is the main reservoir for the State Water Project, which irrigates more than 600,000 acres of Central Valley farmland and serves 20 million urban customers in the San Francisco Bay area and Southern California.
Asked if it would be possible for SWP contractors to receive a 100 percent allocation next spring under the current plan, Leahigh said full deliveries would be difficult to achieve in any event.
“It’s too difficult to say at this time” what the allocation could be, he said. “It’s going to depend on what kind of snowpack we do see this winter.”
He said the DWR’s No. 1 task will be to tailor its operation to the restoration work on the spillway.
Crews are on track to meet their self-imposed Nov. 1 deadline to finish the first phase of a $275.4 million effort to repair and rebuild the nation’s tallest dam’s spillways, which were damaged in February. The project is expected to take two years to complete.
The flood control plan comes as a survey of downriver residents by Assemblyman James Gallagher, R-Yuba City, found most are skeptical of state water regulators’ ability to inspect and maintain the earthen dam.
Most said they were more concerned about potential flaws in dam management than they were about the prospect of a terrorist strike on the dam, which the DWR has cited as a reason for withholding some information about inspections.
More than 85 percent of the 3,322 respondents said the DWR should not be issued a new 50-year Federal Energy Regulatory Commission license to operate the dam until the cause of the spillway collapse has been identified and safety concerns and downstream impacts are addressed, according to the survey.
Mellon noted that an independent board of consultants that was convened after the February spillway crisis is working to address those very issues. The board was set to meet with the DWR for the 13th time on Oct. 19-20.
As for the DWR’s terrorism precautions, Mellon said the agency is working under guidelines set by the U.S. Department of Homeland Security.
“The DWR certainly cares about public safety and that’s what we’re prioritizing with our operation of lake levels and reconstruction of the spillways,” she said.