The U.S. Army Corps of Engineers and Bureau of Reclamation have released a final environmental impact statement regarding a fish passage project at the Lower Yellowstone Dam in Montana.
The Lower Yellowstone River is thought to provide one of the best opportunities for the recovery of pallid sturgeon, which were listed as endangered by the U.S. Fish and Wildlife Service in 1990.
Previous studies have suggested that the Lower Yellowstone's intake diversion dam has impeded the sturgeons' upstream migration and access to spawning and larval drift habitats, eventually leading the Corps and Reclamation to evaluate a number of proposed solutions via the impact statement released last week.
Reclamation said the statement "evaluates and discloses the potential effects of a no action alternative and five action alternatives for improving fish passage," with alternatives including a rock ramp, bypass channel, modified side channel, multiple pumps and multiple pumps with conservative measures. Each of the alternatives also includes a monitoring and adaptive management plan.
The agencies together identified the bypass channel as their preference "based upon it best fulfilling statutory mission and responsibilities, along with the consideration of economic, environmental and technical factors."
"The bypass channel provides a balance of fish and agricultural community needs," USBR Great Plains regional director Mike Ryan said. "The alternative provides the pallid sturgeon a chance at recovery, and allows for the continued viable and effective operation of the Lower Yellowstone Project."
The agencies note that the release of the statement does not constitute a decision, and that they may prepare and issue a record of decision selecting an alternative and implementation no sooner than 30 days after than filing the report with the Environmental Protection Agency.
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