Kiewit Infrastructure workers placed leveling concrete for an access road below four energy dissipator blocks at the Oroville Dam

Oroville Dam's Partially Rebuilt Spillway May Be Used

The 2017/18 Lake Oroville Winter Operations Plan says the main spillway is to be used if the reservoir's elevation reaches 830 feet during the month of April. Current forecasts show inflows may raise the reservoir to near the 830-foot trigger elevation by the middle of next week. On April 3, the elevation was 794 feet.

Forecasts of storms this weekend in the Feather River basin may require the California Department of Water Resources to use Lake Oroville's main spillway, not yet completely rebuilt, this week or next week, the agency reported April 3. The spillway is a flood control outlet that is being rebuilt after erosion was caused by heavy rains in February 2017, which triggered an emergency evacuation of 188,000 downstream residents and necessitated extensive repairs.

The department subsequently created the 2017/18 Lake Oroville Winter Operations Plan to ensure public safety in the event of major storm events. The plan dictates more aggressive outflow from Hyatt Powerplant and potential use of the main spillway if the reservoir's elevation reaches 830 feet during the month of April; the report said the current forecasts show inflows may raise the reservoir to near the 830-foot trigger elevation by the middle of next week. On April 3, the elevation was 794 feet.

DWR began increasing outflows April 3 from Hyatt Powerplant to approximately 10,000 cfs in anticipation of the storms. The total capacity of outflows from Hyatt Powerplant is currently 12,500 cfs. If necessary, the agency said it also can use the River Valve Outlet System, which has an additional maximum outflow capacity of 4,000 cfs.

"DWR's objective for the year has been to minimize use of the main spillway while it is still under construction. However, because forecasts are uncertain, DWR is taking proactive steps such as early notification to downstream communities, regulatory agencies, and construction crews to prepare for possible use of the main spillway next week in the event the lake level reaches an elevation of 830 feet, even after increasing outflows through Hyatt Powerplant," its announcement said.

It said Phase I of the reconstruction of the main spillway was completed in November 2017 to handle outflows of 100,000 cfs. Phase II of construction on the main spillway will begin in May, depending on weather.

If the mail spillway is used this week or next, "inspectors will be closely monitoring the chute and flows," it said, explaining that because Phase I included repair and replacement of the upper chute and end of the chute with structural concrete, and construction of a temporary roller-compacted concrete section in the middle chute, a temporary section with a surface not as smooth as the structural concrete sections, the flow there may be more turbulent than in the upper chute, and additional wear may occur to the surface of the temporary section.

Download Center

HTML - No Current Item Deck
  • Free Safety Management Software Demo

    IndustrySafe Safety Management Software helps organizations to improve safety by providing a comprehensive toolset of software modules to help businesses identify trouble spots; reduce claims, lost days, OSHA fines; and more.

  • The Top 5 Safety and Technology Trends to Watch in 2019

    Get the latest on trends you can expect to hear more about in 2019, including continued growth of mobile safety applications, wearable technology, and smart PPE; autonomous vehicles; pending OSHA recordkeeping rulemaking; and increased adoption of international safety standard, ISO 45001.

  • Get the Ultimate Guide to OSHA Recordkeeping

    OSHA’s Form 300A posting deadline is February 1! Are you prepared? To help answer your key recordkeeping questions, IndustrySafe put together this guide with critical compliance information.

  • Safety Training 101

    When it comes to safety training, no matter the industry, there are always questions regarding requirements and certifications. We’ve put together a guide on key safety training topics, requirements for certifications, and answers to common training questions.

  • Conduct EHS Inspections and Audits

    Record and manage your organization’s inspection data with IndustrySafe’s Inspections module. IndustrySafe’s pre-built forms and checklists may be used as is, or can be customized to better suit the needs of your organization.

  • Industry Safe

OH&S Digital Edition

  • OHS Magazine Digital Edition - January 2019

    January 2019


      Production vs. Safety 
      Meeting the Requirements for Emergency Equipment
      The State of Contractor Safety
      The Three Keys to Effective Chemical Management
    View This Issue