A deep drawdown at the Willamette Valley Project's Cougar Reservoir and new spill operations at Foster Dam are scheduled to commence this fall after U.S. District Judge Marco Hernandez on Sept. 1 issued a final order in Northwest Environmental Defense Center et al. v. U.S. Army Corps of Engineers et al. [18-437].
The decision finalizes the judge's June 14 draft order that found the Corps has broad discretion to use spill, deep drawdowns and water from its power pools to help threatened upper Willamette River Chinook and steelhead, which have continued to decline since the National Marine Fisheries Service issued its 2008 BiOp.
"The actions ordered will have immediate positive impacts on threatened salmon and steelhead," Jennifer Fairbrother, conservation director for plaintiff Native Fish Society, said in a news release. "Operational changes are ordered at multiple dams that will improve downstream volitional fish passage and water quality—two of the main actions needed to recover these populations."
Based on historical generation over the past two decades, it will also result in the average annual lost generation of 12.2 MW, according to a statement from BPA. Cougar Dam has a capacity of 28 MW and generates 17.8 aMW annually.
Bonneville noted the order will likely impact power generation from Oct. 1 until about Jan. 15, given that it calls for a drawdown beginning Oct. 1, with a target pool elevation to reach by Nov. 15 and hold until Dec. 15 before refill can begin.
The deep drawdown at Cougar Dam during peak juvenile spring Chinook migration this fall will draft the reservoir elevation to within 25 feet or less of the regulating outlets. The power impacts of the operation—which holds the reservoir below the minimum power pool—are expected to result in a 60- to 95-percent reduction in power generation during the critical winter power-production period.
Further impacts to power generation are anticipated. "The expert panel established by the court is still engaged in developing proposals for some of these measures," BPA spokesman Kevin Wingert said in an email to Water Power West. "We also anticipate generation impacts at Detroit and Foster [dams], and potentially other projects as operations change as a result of the judicial order. As operations are finalized, we will have a better sense of the overall effect of this ruling," he wrote.
Scott Simms, executive director of the Public Power Council, commented, "We at PPC are still evaluating the judge's order and considering our options. The bottom line is that the Corps needs to work with public power to ensure federal resources are operated in accordance with their congressionally authorized purposes."
The judge's opinion rejected the Corps' argument that it does not have the authority to draw the reservoirs below the power pool during the critical power production period of October through March.
Hernandez found the Corps failed to show drawdowns would abandon its power production purpose or preclude it from generating power at other dams in the Willamette Valley Project. Altogether, the project has a combined capacity of just over 400 MW.
The "power storage allocations represent the amount of impounded water that would be needed to produce enough hydropower to meet regional demand under a worst-case scenario in both the Willamette River and Columbia River," Hernandez reasoned.
In his decision, he turned to the Flood Control Act of 1950, under which the 13 dams in the Willamette Valley Project were built. That act relied on engineer reports that recommended the plan for Willamette projects be authorized as a "general guide" for further development of water resources, and that modifications were at the discretion of the Corps' chief of engineers.
He also noted that deep drawdowns at Cougar and Lookout Point reservoirs do not preclude power generation at other Willamette Valley hydropower facilities, such as Hills Creek, Green Peter and Detroit dams. "Given the highly imperiled status of the listed salmonids, the deep drawdown measures constitute such necessary modifications," he wrote.
A statement from the Corps said it will carefully review the opinion to ensure compliance. "The first injunction actions will begin this fall, which will include a drawdown at Cougar Dam and increased spill operations at Foster Dam. We do not anticipate these actions impacting our flood risk management mission," the statement said.
Further actions will follow at other dams that could include a deep drawdown at Lookout Point Reservoir once a landslide risk assessment is complete, the plaintiffs said in a news release.