CHEYENNE — The developers of what could become the nation's largest wind energy project say the U.S. Bureau of Land Management has overestimated how many eagles could be killed by wind turbines at the site.
They say they're planning a variety of measures to reduce eagle deaths at the $5 billion Chokecherry/Sierra Madre wind power project south of Rawlins, and those steps will result in fewer deaths than the BLM estimate of 46 to 64 per year.
The BLM number is "extremely high," Garry Miller, vice president of land and environmental affairs for the Power Company of Wyoming LLC, said at a public scoping meeting for the project last week in Saratoga.
So how many eagles does the company expect will be killed?
Miller said he's discussing that with the U.S. Fish and Wildlife Service while the company prepares to apply for an eagle take permit for the project's 500-turbine first phase. He declined to give a specific number while that's happening.
The Power Company of Wyoming, a wholly owned affiliate of Denver billionaire Phil Anschutz's The Anschutz Corp., plans eventually to install 1,000 turbines on the sagebrush-covered northern foothills of the Sierra Madre Mountains. That many turbines would generate enough electricity to power 1 million homes.
Eagle take permits give Fish and Wildlife more say to work with industries to prevent eagle deaths. The agency has yet to issue one for a wind farm.
Nevertheless, Fish and Wildlife expects to receive an eagle take application from the Chokecherry/Sierra Madre developers in the weeks ahead. Fish and Wildlife has laid out a review process for the anticipated permit that will take about a year.
Fish and Wildlife officials are aware of the BLM's eagle death estimate but plan to come up with their own estimate based on their own methodologies, said Dave Carlson, project lead for Fish and Wildlife.
"But that definitely caught our attention, in terms of we really need to pay attention to what's going on with this project," Carlson said.
He said the goal is to keep eagle deaths to a minimum and find ways to offset the eagles that will be killed. An offset option might be for the developer to retrofit old power poles in the area that have been a longstanding electrocution risk for eagles, he said.
Company officials say the BLM estimate was drawn from eagle mortality rates at wind farms where measures to protect eagles weren't taken, a caveat the BLM mentioned in its environmental impact statement for the wind farm that included the estimate.
The Power Company of Wyoming has spent 5,000 hours studying eagles in a 700-square-mile area on and around the project site, according to company officials. The site is a roughly 50-50 mix of federal land and private land owned by another Anschutz company, the Overland Trail Cattle Company LLC.
Power Company of Wyoming biologists have identified eagle flight corridors, nesting areas and areas frequented by the birds' prey. The developers plan to keep wind turbines away from places where they're likely to kill eagles.
The company also will look at shutting down certain turbines during eagle nesting season and at other times based on observed eagle activity.
The vast majority of eagles observed at the project site have been golden eagles, which are North America's largest bird of prey. Golden eagles typically eat small, ground-dwelling animals, whereas bald eagles often eat fish and are more common along the Platte River about 15 miles to the east.
The vast majority of the area's golden eagles seem to be resident birds rather than migrating eagles that pass through in the spring or fall, Miller said.
Many of the resident eagles are "bachelors" and "bachelorettes" that are difficult to count. The remainder of the resident population includes 14 to 16 eagles in nesting pairs. The company has documented seven to eight active eagle nests within the survey area but no active nests on the project site within the past two years, Miller said.
Whether the resident eagles are more or less vulnerable to wind turbines in their neighborhood is an unanswered question.
"There's a lot of interest in trying to figure that out," Miller said. "Do the resident eagles kind of get used to it?"
Recent research concludes that the western U.S. golden eagle population is stable.