Lake Oroville Spillways Construction Update May 23, 2018


Construction on upper chute of Lake Oroville main spillway

Workers bore a series of holes to contain the explosives for the next round of controlled blasts to break up the original concrete slab of the upper chute of the Lake Oroville main spillway on May 21, 2018. DWR/2018

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


Construction on the Main Spillway

  • Crews continue to demolish the uppermost 730 feet of the original main spillway chute and have begun using controlled blasting in the center portion of the upper chute.
  • In the middle chute, crews completed demolition of the temporary roller-compacted concrete walls, and are now preparing for construction of sub-drains, slab anchors, and structural concrete slabs and walls.
  • Work continues on the energy dissipators, or dentates, at the bottom of the main spillway. The dentates are being hydro-blasted and rebuilt with reinforced structural concrete and epoxy-coated steel dowels.
  • Crews have begun resurfacing one of the structural concrete slabs that did not meet DWR’s quality control standards on the main spillway last year. The slab has a poor surface finish and the top layer is being removed and replaced with structural concrete.  


Construction on the Emergency Spillway

  • Placement of RCC on the northern half of the splashpad is 78 percent complete.
  • Crews continue to clean and prepare the southern half of the splashpad for RCC placement.
  • Placement of the cap or grade beam on the underground secant pile cutoff wall is complete. The cap will tie the secant piles together and will be secured to the RCC splashpad.


Additional Updates

  • The free access program for day use and boat launching at the Lake Oroville State Recreation Area kicked off last week on May 17 and 18. The public can enjoy additional free access days on June 7-8, July 5-6, August 2-3 and September 6-7. Free access applies to day use and boat launching only.
  • DWR and State Parks also announced yesterday that a trail and access road on the northern shore of the Thermalito Diversion pool will be open to the public for the Memorial Day weekend.
  • Lake levels are currently at 821 feet. As we shared last month, DWR anticipates some water to pass through the gates onto the main spillway until the lake level drops below 813 feet. Crews have put in place a water containment system to collect any water that passes through, which will have no impact on construction.
  • The independent Board of Consultants will meet with DWR for the 18th time next week, on May 29 and 30. BOC Memo #17 has been posted to the Lake Oroville spillways webpage.


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 |