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Overview on the Oroville Dam Facilities and Recent Events
Overview on the Oroville Dam Facilities and Recent Events
15 February 2017

How the Oroville Facilities are Overseen and Regulated

The California Department of Water Resources (DWR) owns and operates the Oroville facilities for a number of uses, including flood control, water supply and recreation.

The key Oroville facilities consist of the dam, the reservoir (lake), the operational spillway, the emergency spillway and the hydroelectric generating facilities.

Oroville Dam, as a hydroelectric generating station, must be licensed by the Federal Energy Regulatory Commission (FERC).

U.S. Army Corps of Engineers (Army Corps) and DWR Division of Safety of Dams (DSOD) share regulatory oversight authority over flood control operations at the Oroville facilities.

While FERC typically has jurisdiction over flood control operations as part of its licensing authority, Congress specifically granted exclusive jurisdiction over flood control operations at the Oroville facilities to the Secretary of the Army in PL 85-500. Additionally, Congress made an appropriation toward the cost of constructing Oroville Dam and Lake Oroville. This appropriation was made contingent upon an agreement between the State of California and the Department of the Army for operation of the dam for flood control benefits.

Oroville Dam has passed all annual and independent inspections regarding the adequacy, stability, and structural integrity of the facilities, including:

  • Annual inspection by FERC
  • Semi-annual inspections by DWR DSOD
  • Five-year Independent Engineer inspection and review

 

Timeline of Recent Events

Beginning January 13, record rainfall in the Feather River watershed led DWR to make reservoir releases from Lake Oroville consistent with flood control rules set by the U.S. Army Corps of Engineers and Division of Dam Safety.

Flows through the operational spillway fluctuated between 0 cubic feet per second (cfs) and 10,000 cfs through January 30. Beginning January 31, flows through the operational spillway increased to more than 10,000 cfs as runoff into the river increased.

On February 7, during routine use, reservoir releases through the operational spillway were increased from 44,500 cfs to 54,500 cfs to offset increased inflows from rainfall.

At that time, DWR discovered a large amount of debris coming out of the concrete-lined channel of the operational spillway. DWR stopped all releases to inspect the damage.

Currently, the cause of the damage to the operational spillway is unknown.

After testing, DWR began to release 20,000 cfs from the operational spillway to offset inflows into Lake Oroville, and continued to increase releases through the operational spillway.

On February 11, the water elevation in Lake Oroville reached 901 feet, leading to flow over the emergency spillway.

On February 12, erosion began to progress up the right side of the emergency spillway. DWR increased the operational spillway releases to 100,000 cfs to draw down the water level, reduce flow over the emergency spillway and assess the erosion.

As of February 14, water levels in Lake Oroville were 13 feet below the crest of the emergency spillway. DWR has begun repairs to the erosion areas below the emergency spillway.

DWR, in full compliance and at the request of FERC oversight authority, is organizing an independent board of consultants – experts in fields including structural engineering and spillway hydraulics – to assess conditions and recommend further actions and facility repairs.

Background on Oroville Facility Licensing Process

In 2005, DWR applied for a renewal of its operating license for the Oroville hydroelectric generating facilities.

During the relicensing process, Friends of the River, Sierra Club and the South Yuba River Citizen’s League filed a motion to intervene in the relicensing. These groups alleged that the emergency spillway at Oroville should be classified as an “operational/auxiliary” spillway and should be armored with concrete, citing the potential for erosion and downstream runoff impacts. During the proceeding, FERC confirmed that the emergency spillway was properly designated and that it met all FERC engineering guidelines.

Friends of the River, Sierra Club and the South Yuba River Citizen’s League in their motion alleged based on a 2002 Yuba County Water Agency Technical Memorandum on Lake Oroville Surcharge that “[a] loss of crest control could not only cause additional damage to project land and facilities but also cause damages and threaten lives in the protected floodplain downstream.” However, the Yuba County Water Agency Report was for the purpose of assessing flood control in Yuba County and did not evaluate the structural integrity of the Oroville emergency spillway.

In their supporting documentation to FERC, the State Water Contractors (SWC) and the Metropolitan Water District of Southern California (MWD) pointed out that the FERC relicensing process was not the appropriate venue to raise flood control measures that go beyond FERC’s jurisdiction, which for Oroville does not include flood control. All these types of flood control issues at Oroville Dam are the jurisdiction of the Army Corps.

SWC and MWD raised no issues regarding the costs of armoring the emergency spillway.

A settlement of the FERC license was reached allowing the Oroville hydroelectric generating facilities to continue hydropower operations until 2008. Each year since 2008, FERC has granted a one-year license extension to for these facilities.