ND Paper says it is investigating the operational issue that led to black liquor being released into the atmosphere and fully cooperating with the Maine Department of Environmental Protection.

Residents of Rumford, Maine, were startled Tuesday when brown snow blanketed the town, caused by a malfunction at the ND Paper Mill. The mill accidentally released black liquor, a byproduct of paper production, into the air, discoloring the snowfall and raising health concerns.

RUMFORD (WGME) -- The Town of Rumford is warning residents to stay away from "brown snow." The town says a malfunction at the mill released spent black liquor, causing tan or brownish snow. This is mostly affecting areas near the mill, like Falmouth Street, Cumberland Street and Waldo Street.

A couple inches of snow fell in Rumford Monday night and Tuesday morning, but in parts of the community, people noticed brown or tan snow falling from the sky. The town said Tuesday there was a malfunction at the paper mill that caused a release of spent black liquor,