Work is underway to repair a five-mile stretch of levee in south Sutter County where officials rushed to make emergency repairs during the Lake Oroville spillway incident of 2017 by putting up a temporary seepage berm.
The $77 million project, being overseen by the U.S. Army Corps of Engineers, will see repairs carried out along the west Feather River levee between Tudor Road and Cypress Avenue, including the installation of cutoff walls as deep as 140 feet into the existing levee. The work will connect two previously completed projects – Star Bend Setback and Laurel Avenue repair – by the Sutter Butte Flood Control Agency.
“This area was impacted by the 2017 Oroville Spillway situation when there were releases of 100,000 cubic feet of water per second (cfs) into the Feather River. This area leaked like a sieve; there was a lot of seepage flowing through and under the levee,” said Michael Bessette, interim executive director for SBFCA. “This (federal project) is great for the community. These five miles were put at risk and really needed to be repaired.”
SBFCA recently completed repairs to 36 miles of levee as part of its Feather River West Levee Project, from the Thermalito Afterbay to Laurel Avenue. These five miles were the last of the needed repairs to the levee as part of that project, though other repairs are still needed along the Sutter Bypass and Wadsworth Canal within the Sutter Basin.
Levee degrade operations for the U.S. Army Corps of Engineers project began last week. Most of the levee will be degraded by at least one-third of its height by the middle of June, with the northern most bit (1,400 feet) being degraded even more in order to allow crews to install a cutoff wall.
Though recent rains caused some temporary delays to levee degrade operations, Bessette said there are no concerns at this time regarding upcoming rains or even the ongoing snowpack runoff into the summer. Flows in the Feather River near the project site (which is south of the confluence of the Feather and Yuba River) are around 15,000 cfs currently and are expected to ramp down over the summer to around 10,000 cfs.
Bessette said that’s a good thing. Flows would have to be around 80,000 cfs for it to pose a threat to the project.
“There have been some concerns raised by people about the level of Lake Oroville and it being filled to 95 percent capacity. That shouldn’t pose a problem for this project if flows into the river stay low and it sounds like they are considering half of the snowpack in the Feather River watershed has already melted,” Bessette said. “… However, if river flows were to dramatically increase above what is anticipated, the contractor has a flood contingency plan in place and would start reconstructing the levee to prevent overtopping.”
About 90 percent of the work needed is expected to be completed this year. The rest of the work will be done next year because bypass systems for irrigation pipelines must be installed but can only be done during the winter months.
The corps has designated $50 million to do the project. The rest is being split between the state and SBFCA, with the state paying up to 70 percent.