March 21 Lake Oroville Spillways Construction Update


Oroville Spillway Splashpad March 12

The splashpad at Lake Oroville will armor the hillside between the emergency spillway and the secant pile wall to prevent erosion if the emergency spillway is ever used again. DWR/March 2018

SACRAMENTO – Today the Department of Water Resources (DWR) provided an update on construction activities for the Lake Oroville Spillways Emergency Recovery Project.


Construction at the Emergency Spillway

  • The underground secant pile cutoff wall was completed March 7, 2018 and marks a major milestone for 2018 construction. The secant pile wall is 1,450 feet long and located 730 feet downhill of the emergency spillway at depths of 35 to 65 feet.
  • On Feb. 28 crews began construction of the roller-compacted concrete (RCC) splashpad, which will cover the hillside between the emergency spillway and secant pile wall. The splashpad, in conjunction with the secant pile wall, will armor the existing terrain to significantly reduce the type of uphill erosion that occurred during the February 2017 incident.
  • Later this year, an RCC buttress will be constructed adjacent to the emergency spillway to provide further reinforcement.


Construction on the Main Spillway

Phase Two of construction on the main spillway is expected to begin in May and is dependent on weather. This year’s work includes:

  • Demolition of the original 730 feet of the upper chute leading to the radial gates and reconstruction with steel-reinforced structural concrete slabs and walls.
  • Placement of 2.5-foot, steel-reinforced structural concrete slabs over the RCC middle chute.
  • Removal of the RCC walls in the middle chute and replacement with structural concrete walls.
  • Hydro-blasting and resurfacing of the energy dissipaters at the base of the main spillway.


DWR also began conducting early preparation work on the RCC middle chute by temporarily sealing its surface. Later this spring, crews will begin resurfacing the top layer of RCC to create a uniform surface before placement of steel-reinforced structural concrete slabs.


Additional Updates

  • At the request of the Federal Energy Regulatory Commission (FERC), DWR submitted its outline to address recommendations and findings in the Independent Forensic Team’s final report.
  • The 2017/18 Lake Oroville Winter Operations Plan will be updated after DWR’s April 1 snowpack survey. The updated Plan will account for snowpack runoff forecasts and reservoir conditions for the remainder of the rainy season.
  • DWR will meet with the Independent Board of Consultants (BOC) for the 16th time on March 28 and 29. DWR will post the BOC’s memo recapping this meeting on the Lake Oroville spillways webpage when it is received.


To view photos and video of the Lake Oroville Spillways construction, visit DWR’s Oroville Spillway photo gallery and YouTube channel.



For more information, follow us on Twitter or Facebook, read our news releases or visit our Oroville Spillway Incident webpage.


Erin Mellon, Assistant Director, Public Affairs, Department of Water Resources

(916) 651-2440