FOX 21 News, KQDS-DT

MADISON - The Minnesota DNR say two silica sand mining companies may be prosecuted for pollution violations.

The agency said these are the first two cases referred to the Department of Justice since the sand mining boom started.

The DNR alleges Preferred Sands of Minnesota failed to have a plan in place when an embankment collapsed at a Trempealeau County mine.

The DNR reported more than 2,100 feet of river mud went into privately owned land.