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Oroville SpillwayWhat a difference a day makes!  As of Friday afternoon, it appeared unlikely that Oroville Reservoir would rise enough for water to flow over the emergency spillway, as inflow into the lake had been declining since early Friday, the rain had stopped, and the primary spillway continued to be used to manage outflow. But the gaping hole in the spillway, coupled with concerns about downstream flooding, resulted in the story traveling all the way back to New York.  And with the latest inflow figures and DWR’s modified release schedule from the Primary Spillway, the emergency spillway actually started spilling on Saturday morning.

Here is a really helpful summary for going into the weekend:

  1. As of Friday afternoon DWR did not believe water would flow over the emergency/auxiliary spillway, and assumed it could continue to release 65,000 cfs through the dam’s primary spillway. 65,000 cfs releases were anticipated to keep the lake level below the emergency spillway.  Watch footage from Action News Now of Chico-Redding for what 65,000 cfs running through a damaged spillway looks like.  However, late Friday night DWR changed the releases to 55,000 to arrest erosion.
  2. As inflow into the lake continued to drop (from a high of over 190,000 cfs late Thursday night to about 125,000 cfs Friday afternoon), DWR anticipated that the lake level would start to drop sometime on Sunday. In fact, though, late Friday night the inflow did not drop as quickly as anticipated, and as of Saturday morning it was still at 95,000 cfs.  Thus, some water has started running over the emergency spillway.
  3. The National Weather Service predicts some precipitation starting next Wednesday, but the anticipated precipitation from this next storm may not be enough to result in a lake level that will again spill over the emergency spillway.

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    Photo by Briantravelman
  4.  Authorities have placed boom lines in the diversion pool upstream of the Thermalito diversion dam to capture any debris that is collected along the way from water running down the emergency spillway. Authorities cleared some trees in the area immediately below the emergency spillway to minimize any debris that could end up in the river.  Here is a picture from Google Earth taken by user Briantravelman that shows the trees that could become debris in the river (hopefully the cows are no longer there).
  5. DWR continues to monitor erosion from the crater in the spillway, and now believes it will continue to be able to release 55,000 cfs without additional erosion (erosion to date has moved about 200 feet up the spillway, and if not controlled much beyond that could damage the spillway gates).  However, since DWR believed it could run the Primary Spillway at 65,000 cos, this is obviously subject to change.  Officials believe further erosion is unlikely to occur because of hard bedrock underneath the spillway at the current point where erosion stops.

For more detailed information about current storage, inflow and outflow from Oroville Dam, we recommend the California Data Exchange Center.

Additional sources of information on this incident can be found on the DWR website.

Look for further updates as we consider the consequences of future storm events until the primary spillway can be repaired.

Photo of Scott L. Shapiro Scott L. Shapiro

Scott Shapiro is known for his expertise in flood protection improvement projects throughout California’s Central Valley. He is helping clients with more than a billion dollars in projects in California’s Central Valley and issues involving the Federal Emergency Management Agency (FEMA) and the…

Scott Shapiro is known for his expertise in flood protection improvement projects throughout California’s Central Valley. He is helping clients with more than a billion dollars in projects in California’s Central Valley and issues involving the Federal Emergency Management Agency (FEMA) and the U.S. Army Corps of Engineers (USACE) throughout the Western United States.

With a special focus on massive flood protection improvement projects, Scott advises clients through regulatory, contractual, financing, and legislative challenges. Acting as general or special counsel, he regularly interacts with senior management at USACE (Headquarters, South Pacific Division, and Sacramento District), the California Department of Water Resources, and the Central Valley Flood Protection Board. He was named to the National Section 408 Task Force and has been invited to give testimony to the National Academies. Scott was instrumental in helping the first regional flood improvement agency that took a basin threatened by flood risk from less than 30-year level of protection to a level of protection approaching 200-year.

Having worked with FEMA on issues of floodplain mapping and levee accreditation for many years, Scott has developed collaborative environments in which he fosters win-win solutions for his clients. He is also currently serving as the lead counsel on a flood insurance rate map (FIRM) appeal and has drafted Federal legislation to modify the National Flood Insurance Program (NFIP) several times.

Scott is known throughout the region for his extensive litigation experience focusing on cases arising from levee failures. He has litigated levee failures resulting from underseepage, failed encroachments, and rodent burrows as well as briefing levee overtopping cases at the appellate level. Scott is one of the few attorneys with experience litigating flood cases on behalf of plaintiffs as well as defendant government entities.

Photo of Andrea P. Clark Andrea P. Clark

Andrea Clark specializes in water rights and flood control, serving as general counsel to a variety of public agencies from local reclamation districts and water districts to regional joint powers authorities.

Public agencies in the water and flood control fields rely on Andrea…

Andrea Clark specializes in water rights and flood control, serving as general counsel to a variety of public agencies from local reclamation districts and water districts to regional joint powers authorities.

Public agencies in the water and flood control fields rely on Andrea for her ability to explain in understandable terms the wide range of issues impacting them, including basic transparency laws (Brown Act and Public Records Act), public bidding and contracting, bond financing, the unique nature of joint powers authorities, and elections. She also regularly counsels clients on water transfers, Proposition 218 compliance, the California Environmental Quality Act, the National Environmental Policy Act, and financing strategies for major capital improvement projects.

With a special expertise in flood control and floodplain management, Andrea is regularly asked to speak on topics ranging from flood insurance to climate change and the future of flood control policy in California. Through her representation of clients in state flood policy and speaking engagements, she has forged strong relationships with key members of the flood control community in California.

Andrea also counsels private clients, including landowners and mutual water companies, on water supply matters, including proceedings before the State Water Resources Control Board, water rights determinations, and contractual disputes with Federal agencies.