Marijuana growing operations in Wisconsin, watch out: the U.S. Forest Service has instructed hunters to look out for fields in the state's Chequamegon-Nicolet National Forest, reported CNN.

In August, one fisherman in the state came upon a 8,000-plant growing operation worth $8 million.

"Chequamegon-Nicolet National Forest is large, secluded and heavily roaded, so our personnel cannot by themselves keep an eye on every acre,," said Jane Cliff, spokesperson for the U.S. Forest Service's eastern region.

One Justice Department director explained that growers, rather than creating one large field of marijuana plants, now plant a larger number of smaller fields to thwart aerial detection.

Wisconsin claims that many of the operations are armed and make the state forests dangerous for citizens.

There are also environmental concerns.

"It causes a lot of environmental damage from soil erosion and it increases sedimentation in rivers and streams which affects the fish. There is possibility of chemical runoff from poisons and other wastes," said Suzanne Flory, a public affairs officer with the state forest.

Police interviews with those who have been apprehended on growing operations revealed that most were undocumented immigrants. Some claim they were sent from California knowing their eventual task, but others say they were unaware they would be growing marijuana and did not know what state they were working in.

[Image via AFP]