Contractors remove sediment and debris below the Oroville Dam flood control spillway. Dale Kolke/DWR

Good day! Today we feature a series of little squibs of what has been happening in the past two weeks.  All of the information below is confirmed, and all of it is notated with additional context.  But we did want to share with you one item, which we cannot confirm, but which we are hearing about.  Rumor has it that DWR has already designed significant parts of the spillway repair for Lake Oroville, has had meetings with four hand-selected contractors, and is currently getting ready to award a contract for the first phase of the repair dealing with road construction.  These same rumors peg completion of the project to December 15, an aggressive schedule for any project let alone one this complicated.

The rumors indicate that the spillway will be repaired with roller compacted concrete.  The advantages of this technique include the speed with which concrete can be poured and will cure, and the fact that form construction is either very basic or not necessary at all.  While just a rumor, this technique certainly makes sense in light of the constraints we see.  Unfortunately, California remains very skimpy with its willingness to share information.

As to the details on the ground, here are our top nine items:

  1. DWR ran water over the principal spillway during the second half of March, but since March 28 only the Hyatt Powerplant has been releasing water, and at about 10,000 cfs. Storage in Lake Oroville sits at around 844 feet as of April 5. DWR has indicated that it intends to use the principal spillway one or two more times before June 1 to manage flows from snowmelt (see #9, below, for snowpack information). As a result, the river has seen flows of about 10,000 cfs or 50,000 cfs, but almost nothing in between. These flows are very rough on the banks and waterside levee toes.
  2. What will the spillway repairs cost? There does not appear to be a firm cost estimate to date, but DWR in late March estimated that repairs to the principal spillway could cost between $100 and $200 million. Presumably we will know more once DWR announces its intended repair plan, which was supposed to be released by the end of March.
  3. When will the repairs be completed? DWR has said that it will be expediting work in order to have a fully functional spillway prior to the start of the next storm season; however, it is unclear at this point whether the repair work can be completed in time for next year’s wet weather. The Sacramento Bee reported on March 23 that an independent panel of experts hired by DWR is doubtful that repairs can be completed in time. In the meantime, we await a repair plan that was reportedly going to be revealed by DWR by the end of March.
  4. DWR is also facing criticism over a decision to keep confidential additional documents related to the spillway, including an additional memo by the independent panel of experts and a safety compliance report. The Sacramento Bee reported on this here.
  5. It remains to be seen whether the Oroville Dam issues this winter will impact water supply deliveries throughout the State this year. Oroville Dam is critical to the State Water Project, which delivers water to municipal and agricultural districts throughout the State, including the Metropolitan Water District of Southern California. DWR may want to keep lake levels lower than normal this spring and summer, which theoretically could impact supplies for contractors down south.
  6. On April 2, President Trump approved a major disaster declaration that includes the February storms that led to the Oroville Dam spillway issues. See here for FEMA’s news release. This means federal funds will be available for debris removal, emergency protective measures, repair of public facilities, and hazard mitigation projects.  State and local agencies are preparing requests for federal dollars for measures taken to mitigate for the Oroville principal spillway damage.
  7. Some have wondered whether California would be left in the dark on disaster declarations after much of the rhetoric between the President and Governor Brown. This article makes for great reading on a more complex analysis of that issue.
  8. A new series of storms – including high winds – is expected to arrive in Northern California by the end of this week, with 1-2 inches of rain expected in the Sacramento Valley. See here for the National Weather Service precipitation forecast.
  9. Statewide snowpack is 164% of average as of the March 31 DWR snow survey. See DWR’s press release for more details.

Tune in again for more updates as we get them.