Chokecherry and Sierra Madre, the largest onshore wind farm planned in the United States, would annually kill 10 to 14 golden eagles, the U.S. Fish and Wildlife Service projected in a draft environmental study released Wednesday.
That figure represents a substantial reduction from the 46 to 64 golden eagle fatalities estimated by the U.S. Bureau of Land Management in 2012.
Federal officials attributed the decline to several factors. The permit application submitted by the project’s developer, Power Company of Wyoming, only considers the 500 turbines proposed in the project’s first phase. A second phase calls for an additional 500 turbines.
But the decrease is also the result of years of planning aimed at reducing eagle deaths, they noted. Power Company of Wyoming had not developed an eagle conservation strategy when the BLM released its projections in 2012.
“We appreciate the company took seriously the recommendations and advice we gave them as they were developing their eagle conservation plan,” said Clint Riley, assistant regional director for the Fish and Wildlife Service’s Mountain-Prairie region.
Eagle deaths have emerged as a sizable hurdle for would-be wind developers in recent years.
A North Carolina power company was fined $1 million for killing more than 150 species protected under the Migratory Bird Treaty Act over a four-year period at a wind farm outside Glenrock in 2013.
Industry officials and environmentalists have also clashed over the length of so called “take permits” granted to wind farms, which enable turbine operators to kill a certain number of eagles annually without being prosecuted. A Fish and Wildlife proposal to grant permits for up to 30 years was reversed by a federal judge last year. The current length is five years.
Wind developers have filed a series of applications for take permits in recent years, but only one facility in the country has been permitted to-date.
Chokecherry and Sierra Madre, a 3,000-megawatt wind farm proposed for Carbon County in south-central Wyoming, is the first facility in the Rocky Mountain region to have a draft environmental impact study completed.
Power Company of Wyoming has developed two conservation plans aimed at mitigating avian deaths, one for eagles, the other for birds and bats.
The Denver-based developer, an Anschutz Corp. subsidiary, has proposed designating 105,000 acres, or roughly a third of Overland Trail Cattle Co. ranch, where the project will be located, as “turbine no-build areas.”
Those areas were identified following 5,000 hours of avian surveys between 2010 and 2015, said Kara Choquette, a Power Company of Wyoming spokeswoman.
“That kind of data was used to say what types of airspace do raptors use the most, and not use,” she said.
The company has also proposed putting 27,500 acres into a conservation easement. That move is aimed at bolstering sage grouse habitat, but could have an indirect impact on eagles, Choquette noted. Eagles prey on sage grouse, and more grouse in that area could help direct the birds away from the turbines, she said.
The public will have 60 days to comment on the Fish and Wildlife Service’s draft findings. Public hearings are scheduled for Saratoga and Rawlins in June.
The Fish and Wildlife Service did not identify a preferred alternative in its draft environmental impact statement, as the BLM often does in its reviews.
Instead, the service sought to assess the potential environmental impact of the project, said Riley, the regional assistant director. The golden eagle fatality projection was based on a peer-reviewed model developed by a third party. The service expects one to two bald eagles would be killed annually, Riley said.
After public comment is received and the environmental impact statement completed, Fish and Wildlife will decide whether to issue Chokecherry a permit.
Follow energy reporter Benjamin Storrow on Twitter @bstorrow