A state appeals court panel heard arguments Thursday from a sand mine owner protesting a Department of Natural Resources (DNR) ruling that the mine cannot operate without a special permit because of its proximity to a trout stream.

Asking that the state’s ruling be reversed, an attorney for mine owners Tracie and Michelle Erickson of Rushford, Minn., argued that the mine, in existence since 1992, should be exempt from the trout stream setback law passed by the Legislature two years ago.

A lawyer for the state countered that the mine’s permit lapsed in early 2013, triggering the requirement that it meet new setback standards.

The appeals court has 90 days to issue a ruling.

The hearing was only the latest turn for the Erickson mine, which has been at the center of a contentious battle in southeast Houston County between mining interests and neighbors and others who fear that a profusion of silica sand mines built for the fracking industry threaten the water, bluffs and quality of life in southeastern Minnesota.

Neighbors have turned on neighbors, public meetings have erupted into shouting matches, and the Houston County zoning inspector has been disciplined for threatening to issue zoning violations to people who oppose the mine.

At Thursday’s hearing, one of the Ericksons’ neighbors had to watch the proceedings on video from an adjacent room because of a restraining order issued against him.

Thursday’s arguments centered on the mine’s origins and whether it should be considered a new or an existing project. The DNR’s authority to require a review of the mine’s potential to disrupt the trout stream, Ferndale Creek, rests on whether it was in existence before the law was created two years ago. Ferndale Creek, which is home to brook and brown trout, sits about 1,500 feet from the mine.

A 1992 permit allowed for the excavation of 10,000 cubic yards of silica sand for a bridge project. The permit was good for five years and has been renewed several times.

The mine has some 2 million cubic yards of silica sand, and an earlier proposal would have seen the Ericksons partner with mining company Minnesota Sands to excavate, process and truck all of it out of the site. Concerned that the plan exceeded the original permit for the mine, the county issued a stop work order in 2012. County officials also ordered an environmental review.

The original permit was set to expire in January of 2013, and when Erickson applied to renew it, county officials told him it could not be renewed while the environmental review was underway. When Erickson later that year backed out of the deal with Minnesota Sands, the county issued a permit in 2014 to mine 10,000 cubic yards. The Ericksons’ attorney, Julie Nagorski, said the permit was perpetual and never expired.