The second year of a two-year agreement for spilling water at lower Snake and Columbia river dams was a success in terms of fish passage, downstream survival and hydropower sales, representatives of the agencies and tribes that negotiated the agreement told the Northwest Power and Conservation Council last month.
Whether the flexible operations produced more adult fish won’t be known for at least two years, when fish begin returning from the ocean.
The 2019-2021 Flexible Spill Agreement called for increased spill to aid juvenile fish passage when power prices are low and reduced spill to allow additional power generation when prices are higher. In general, depending on river conditions, spill was decreased for 16 hours of the day and increased for eight hours.
Because of the innovative spill, juvenile fish passed the dams faster than usual, fish survival through the system was higher than usual and fewer fish were transported downriver in barges. In addition, fewer fish passed the dams through the turbine pits, thus decreasing the “powerhouse encounter probability,” an important measure of fish survival.
The flexible spill regime increased hydropower income for Bonneville Power Administration by about $4.7 million. One issue the U.S. Army Corps of Engineers, which operates the dams, will study further is whether the spill increases caused any damage in the tailrace area below each dam.
Ben Zelinsky, senior policy advisor, BPA, said the operations met goals in the agreement for fish benefits, power benefits and operational feasibility. Implementation of the agreement also avoided litigation while federal agencies completed an environmental impact statement and biological opinion on Columbia and Snake river dam operations, a stipulation of the agreement.
The agreement was signed in December 2018 by representatives of the states of Oregon and Washington, the Nez Perce Tribe, BPA, the Corps, and the Bureau of Reclamation. The agreement and the commitment to the flexible spill operation included in the agreement ended in 2020. But, the preferred alternative in the 2020 Columbia River System EIS and the 2020 NOAA Fisheries biological opinion on river operations to protect Endangered Species Act-listed salmon and steelhead included the flex spill operation as a baseline operation in 2021, to be adaptively managed in future years.
A coalition of environmental and fishing groups, the state of Oregon, the Spokane Tribe, and the Coeur d’Alene Tribe all sent notices to the federal agencies announcing their intent to file litigation over the 2020 Biological Opinion and EIS — which include the flexible-spill operations. The environmental and fishing groups and the Spokane and Coeur d’Alene tribes subsequently filed petitions for review with the Ninth Circuit reserving their challenges against BPA for judicial review. No litigation has yet been filed in federal district court.
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