HomeMy WebLinkAboutSpillway Update Menchaca, Clarissa
From: Pickett, Andy
Sent: Thursday, February 9, 20172:10PM
To: BQ5; D�eptHeads
Cc: [AO Administration (AU Employees)
Subject: Spillway update
Attachments: 820917spiUwavf|ovv.pdf
Attached is the latest press release from DVVR.
A DWR press conference has just finished. Staff emphasized that the dam is safe and unaffected by the erosion of the
spillway. The incident isabout handling the outflows ofwater from the lake imorder tomake room for the storm
inflows. Staff explained that they pUanunusing the damaged spillway to release additional water.They are anticipating
this will further erode the spillway, but it does not create a public safety risk. it will create turbidity ln the water,so the
flows will continue to be muddy.
|mthe event the regular spillway can^tbeused (which would bethe case iferosion happens uphi||),the emergency
spillway iaable tnhandle the necessary outflow. CAL FIRE iscooperating with DVVRand has sent crews and equipment
to clear the path along the ravine where the emergency spillway flows.
Sheriff Honea spoke at the conference and explained that he and his staff a re working closely with DVVRand other
partners.They currently do not anticipate any public safety issues downstream, but are planning just incase. The Sheriff
has assigned Sgt.Jack Storne to be in the Incident Command Post. The Sheriff explained the various methods of keeping
residents updated, which includes the County website at his web page at
his Facebumkpage et
and his Twitter feed at . The sheriff encouraged individuals tosign mpfor telephone
notifications, which can bedone onhis web page.
Additionally, Butte County Fire will be opening up a call center this afternoon at 5301-538-7826 where individuals can get
information.
You can watch the hour-long press conference here: ?
Andy Pickett
Deputy ChiiefAdministrative Officer
Butte County Administration
25 County Center Drive, Suite 200, Oroville, CA 95965
T: 530.538.7052 1 W 530.230.7762
U�_D1
./ .
1S pf tYAreg9
p _ 9
CAV
February 9, 2017
Contact:
Ted Thomas, Information Officer— (916) 653-9712
Ted.Thomas@water.ca.gov
Doug Carlson, Information Officer— (916) 653-5114; mobile (916) 335-2299
Doug.Carlson@water.ca.gov
DWR Increases Oroville Spillway Flows
Oroville, Calif. — California Department of Water Resources (DWR) personnel and a host of
collaborating agencies continued to monitor Lake Oroville spillway flows through the night. As
expected, the overnight flow rate of 20,000 cubic feet per second (cfs) caused additional lower
spillway erosion. Spillway flow was stopped again for a few hours this morning to allow engineers to
evaluate the integrity of the structure.
There is no imminent or expected threat to public safety or the integrity of Oroville Dam.
After conferring with State and federal dam safety entities, this morning DWR will ramp up flows down
the spillway to 35,000 cfs. More erosion is expected, but the releases will help operators absorb the
inflow of the storm expected today and tomorrow. DWR first noticed erosion on the spillway Tuesday
morning and shut off flows to investigate.
Engineers from DWR's Oroville Field Division, Dam Safety Branch, Division of Engineering, the
Division of Safety of Dams, and the Federal Energy Regulatory Commission's Dam Safety Branch
are working jointly to monitor the condition of the spillway chute to determine the maximum spillway
flow rate that is safe. The spillway will be monitored continuously by on-site engineers and also with
video and drones.
As a contingency, DWR also is preparing to use the emergency spillway at the dam. Lake Oroville
would naturally flow over this ungated concrete crest, into a mostly unlined emergency spillway if the
reservoir reaches 901 feet elevation. This would be the first time the spillway has been used in the
dam's 48-year history although the reservoir came within one foot of flowing over in January 1997.
The reservoir, with maximum capacity of 3.5 million acre-feet, now holds approximately 3.22 million
acre-feet and stands at an elevation of 880 feet, which is 90% of capacity. As of this morning, inflow
to the reservoir was roughly 118,000 cfs, while 13,000 cfs was being released through the Hyatt
Power Plant before the spillway reopened.
In preparation for the potential use of the emergency spillway, DWR has been clearing trees, rocks,
and other debris from the hillside near the dam where water will flow. CAL FIRE crews have been
mobilized to clear approximately 50 to 100 acres of trees and brush that could be affected by water
releases. These efforts would reduce the potential debris flow into the Diversion Pool and Feather
River. DWR Crews are also placing debris booms in several key areas in the Diversion Pool. To
protect the young salmon and steelhead downstream at the Feather River Hatchery from a large load
of sediment and turbidity, the California Department of Fish and Wildlife began Thursday to evacuate
fish from raceways to the Thermalito Annex and is exploring options for remaining fish eggs, which
are in a susceptible state.
If the emergency spillway is used, flows would start gradually and reach a maximum level within the
design capacity of downstream channels.
Crews will continuously monitor inflows, outflows, the spillway condition, and all aspects of the darn's
operations to protect Oroville Dam and ensure the safety of the public.
Fluctuations in Feather River flows should be expected over the next several days because spillway
flows may be started and stopped as necessary to evaluate the spillway condition as outflows are
increased.
Lake conditions, including lake levels, inflows, and outflows can be obtained via a recorded message
at 530-534-2307.
The news media will be updated on DWR's Lake Oroville flood management plans at noon today at
400 Glen Drive, Oroville.
Visit drought.ca.gov to learn how California is promoting water conservation.
Save Our
)VATEP,q.,