High river flows generating a temporary oversupply of hydroelectricity caused the Bonneville Power Administration (BPA) to partially and temporarily limit the output of wind, fossil-fuel and other thermal power generation on Wednesday night.
Beginning at 12 a.m. Wednesday, the BPA first limited all coal, natural-gas and other thermal generation to minimum levels required for grid stability and safety. The administration then limited approximately 200 MW to 350 MW of wind power generation until 5 a.m. Wednesday, totaling approximately 1,400 MWh. There is currently more than 3,500 MW of wind energy connected to the BPA system.
Rising runoff has pushed dissolved gas levels at most of the eight federal dams on the Lower Snake and Columbia Rivers above 120%, exceeding Washington and Oregon water-quality standards and threatening protected salmon and steelhead, according to the BPA.
The BPA says the action was required to protect salmon and steelhead, maintain the reliability of the power grid and avoid shifting costs to customers. The decision came as the U.S. Army Corps of Engineers increased river flows to maintain space in upstream reservoirs for further runoff from the largest Northwest snowpack since 1997. The Corps of Engineers, Bureau of Reclamation and BPA are required under a court order to manage spill levels to protect fish.
The BPA will provide updates on further generation limits, if any, at 9 a.m. PDT and 3 p.m. PDT each business day at bpa.gov.