The DNR said someone has been setting wildfires near Cloquet, just south of Duluth.
DNR Fire Manager Mark Wurdeman said more than 30 fires have been set this spring, apparently by a single arsonist.
"They all appear to be related. They're road side starts. Folks that live in the area or travel to the area I'm sure have seen the black patches along the the roads, and those are the areas we're looking at," he said.
The most recent was two nights ago. Wurdeman said the fires are near the Fond Du Lac reservation, but they're not all on reservation property.
"What we're looking at now is some help from the public to come forward if they know anything about the suspicious fires that have been started out there," Wurdeman said.
So far, the fires have remained relatively small. No one has been injured and no homes have burned. But officials worry about the arson, particularly as the region continues drying and the fire danger escalates.
Wurdeman said people with information or suspicions can call the state arson tip line: 1-800-47-ARSON.