ST. PAUL  — The Minnesota Court of Appeals has overturned a state Department of Natural Resources decision that prevented a silica sand mine from operating in Minnesota’s Houston County.

The agency  said the Erickson Sand Mine in Houston couldn’t operate until getting a trout stream setback permit, and considered it a new project because its conditional use permit had expired.

According to a press release, the court ruling issued Monday said the mining operation is not a new project, and therefore didn’t need the trout stream permit.

The ruling allows the mine to legally operate. It has been open since 1992, and was set to expand under new ownership.

Silica sand is used by the oil-and-gas industry for hydraulic fracturing.