From the Department of Water Resources:
The following is a regular update from the Department of Water Resources (DWR) on the Lake Oroville Spillways recovery project activities.
Transition from Incident Emergency Response to Incident Emergency Recovery
The California Department of Water Resources (DWR) on Sunday completed transition from Incident Emergency Response to Incident Emergency Recovery at the damaged Lake Oroville spillways.
Emergency Recovery includes construction of the main spillway and the emergency spillway throughout the summer and fall. The main spillway will be operational by November 1 to accommodate flows from winter storms. Additional work will begin again in 2018 to complete reconstruction of both spillways.
Main spillway gate closure
DWR will begin ramping down outflows from the main spillway on Friday, May 19 at 9:00 a.m., with outflows expected to stop by Friday afternoon. The gates at the main spillway are closing to accommodate the construction work on the main spillway.
“We are making gradual changes to outflows and river levels and will continue to adjust as we balance community concerns, regulatory requirements and Mother Nature,” said Acting Director Bill Croyle.
DWR intends to keep the gates at the main spillway closed for the remainder of the season.
DWR plans to reduce outflows from the main spillway to zero on May 19 starting at 9:30 AM. Real-time monitoring of erosion conditions may require a faster gate closure. As part of the ongoing site preparation work that is underway in addition to the upcoming use of the main spillway, some soil and concrete may be dislodged from the spillway structure. This is expected and will not delay construction.
To balance flows in the Feather River, the Hyatt Powerplant flows are expected to ramp up from 5,000 cfs to 8,100 cfs on May 19 at approximately 1:00 p.m.
Penstock 1 at Hyatt Powerplant is expected to come online after routine and scheduled maintenance early next week. Once Penstock 1 is back in use, Hyatt Powerplant will have the ability to release 13,000 cfs. The River Valves Outlet System has the capacity to release an additional 4,000 cfs should DWR deem it necessary. A contingency plan is in place should reservoir levels require that the main spillway be used once more this spring or summer.
Forecast Flows in the Feather River
The forecast flows downstream in the Feather River will be a gradual transition over four days.
- 20,550 cfs to 10,550 cfs on May 19 from approximately 5:30 a.m. to approximately 7:30 p.m. on May 19.
- 10,550 cfs to 5,300 cfs on May 19 from approximately 7:30 p.m. to approximately noon on May 21.
- 5,300 cfs to 9,800 cfs over 48 hours beginning as early as May 21 at 7:30 p.m.
Kiewit Infrastructure West Co. is expected to ramp up construction work on May 22. The complete recovery or replacement of the spillways will be done in multiple phases due to the enormity of the project and the time limitations of the construction season.
Work has already started on portions of work like road construction and slope stabilization in and around future work areas which needs to be completed regardless of spillway recovery design decisions.
The public can watch construction activities through a live feed from two cameras at the site. Hosted by the California Department of Parks and Recreation, the Lake Oroville State Recreation Area Spillway Live Stream is at www.parks.ca.gov/live/lakeorovillesra_spillway. Later this summer, the live feed will also be available at the Oroville Visitor Center.