A single high-powered round was fired into a turbine at the Golden West Wind Energy Center near North Yoder Road and Heaston Road, authorities said.
The damage is estimated between $20,000 and $250,000.
In a news release Thursday, the Sheriff's Office noted that the center "has been at the center of controversy with some citizens who were opposed to the project."
The turbine is part of a wind farm under construction by NextEra Energy Resources, which is erecting 145 turbines and 300 transmission structures on the eastern plains of the county.
Neighbors filed a lawsuit this year to try to stop the project, but it was dismissed in September after the group, El Paso County Property Right Coalition, reached an agreement with the county.
The El Paso County Commission approved the project in 2013, with an underground power line.
But in February, commissioners agreed to an amended plan that includes a 29-mile above-ground power line with poles strewn across a patchwork of private properties.
That decision, in particular, rankled many county residents, who were angry that their mountain views would be obscured.
Others raised concerns over the potential negative health impacts of living next to the lines. But more than 160 residents leased NextEra some of their land, and many longtime ranchers in the area hailed the project as a much-needed economic boost.