Plan in place as Isabella nears capacity

Lake communities on alert as Oroville spillway crisis looms

Rebecca Neipp

News Review Staff Writer

As crews worked overtime to shore up the compromised Oroville Dam before the next series of storms hit this weekend, concerns about Lake Isabella’s dam — once classified as the most dangerous in the nation — resurfaced as runoff continued to nudge the lake toward capacity.

“One important thing to keep in mind while we are having this conversation is that it’s difficult to draw a parallel between what’s happening in Oroville and what may or may not happen in Isabella,” said Rick Brown, senior public affairs specialist for the U.S. Army Corps of Engineers.

“These are two entirely different locations under completely different circumstances.”

Brown said that when Isabella was identified as one of the most high-risk dams in the ACE’s portfolio, the corps promptly assessed the dangers and put together a mitigation plan.

Part of that plan was putting lake-level restrictions into place while engineers made necessary improvements.

“We have already begun smaller construction projects, in terms of relocating Forest Service facilities that will be in the footprint of the new emergency spillway,” he said. “Those are expected to be completed later this fall.

For the last several years, California’s historic drought facilitated a natural drop in lake levels — which only recently began to climb when storms began pummeling the Sierra Nevada.

“Now we are getting close to those restricted levels. But it’s important for folks to understand there is no concern that we are in a danger zone.”

Brown said that once the ceiling is reached, a plan for mitigation is triggered.

As of this week, the North and South forks of the Kern River were feeding some 4,000 cubic feet per second into the lake. The current outflow — which is being diverted on the west side of the mountains toward Bakersfield — is approximately 1,850 CFPS.

Brown said that as the inflow has climbed, the outflow has been adjusted each day to compensate. “Once we reach our capacity [360,000 acre feet], we will increase our outflow accordingly.”

Although that day is nearing, he declined to speculate when exactly it would happen.

“I don’t want to say there are no concerns, because there are — that’s why the Army Corps of Engineers got involved in the first place,” he said.

“But we have temporary flood-control restraints in place, we have folks walking the dams every day, inspecting them to make sure there are no problems. We are releasing outflow downstream in a responsible way that won’t cause flooding or erosion.

“I can comfortably say that there are no issues beyond those that have already been identified, and are currently being addressed.”

House Majority Leader Kevin McCarthy, who represents the Kern River Valley, acknowledged concerns in a recent statement. He said that ACE Sacramento District Commander Col. David Ray “has assured me that Lake Isabella is safe.

“Over the years, I have worked to hold the Corps accountable to the timeline needed to expeditiously complete the safety work needed at main and auxiliary dams at Lake Isabella … This weekend’s events at Oroville Dam only further demonstrate the neet to get the repairs at Isabella done quickly.”

McCarthy said that to date he has helped secure $85 million in funding toward that end.

“While our parched state has been blessed with much-needed rain and snow this year, I will remain vigilant and continue to work with our community partners and the Corps to ensure that our dams remain safe.”

Story First Published: 2017-02-17