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The Karner blue butterfly’s range “almost perfectly overlaps” that of sand deposits where frac sand miners might go, according to a Wisconsin Department of Natural Resources memo. Shown here in blue are the areas where butterflies are at least 50 percent likely to occur, including a five-mile buffer, sandstone of possible interest to frac sand miners, and frac sand mines or plants.

This map shows the DNR’s January 2012 list of sites with air pollution permits. So it doesn’t include sites that don’t yet have such permits. As of mid-January, the DNR had counted about 60 mines, 32 plants either operating or being built, and 20 more proposed mines — more than double the 41 mines or plants the Wisconsin Center for Investigative Journalism counted in mid-July. The agency conservatively estimated the state’s capacity at more than 12 million tons of sand a year.

Main story: Are frac sand miners failing to check for rare butterfly?


Data sources: Frac sand sites, Wisconsin Department of Natural Resources; sand deposits, U.S. Geological Survey. The butterfly high probability range, a probability model, was produced by David Mladenoff of UW-Madison’s Forest Ecology Lab. Map: Kate Golden, Wisconsin Center for Investigative Journalism.

The nonprofit Wisconsin Center for Investigative Journalism ( collaborates with Wisconsin Public Radio, Wisconsin Public Television, other news media and the UW-Madison School of Journalism and Mass Communication. All works created, published, posted or disseminated by the Center do not necessarily reflect the views or opinions of UW-Madison or any of its affiliates.

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Kate GoldenMultimedia director and reporter

Kate Golden, multimedia director and reporter, specializes in environmental stories and data visualizations.