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There’s a new wrinkle in Wisconsin’s fast-growing frac sand mining: It turns out that an endangered butterfly, the Karner blue, lives in the same region. And some companies may be failing to check for the butterfly as they move ahead with mining operations.

This western Wisconsin community is in the midst of a land rush — call it a sand rush — fueled by exploding nationwide demand for fine silica sand used in hydraulic fracturing of oil and natural gas. At least 16 frac sand mines and processing facilities are operating, and an additional 25 sites are proposed, in a diagonal swath stretching across 15 Wisconsin counties from Burnett to Columbia, the Center has found.