Ганнисон
Contamination of the Gunnison River with selenium and mercury results from irrigation of high-selenium soils derived from the Mancos Shale and from mineral mining. The region surround the Gunnison River is also part of the Colorado Mineral Belt. Contamination of the Gunnison River with selenium and mercury is a conservation concern for the bonytail chub, Colorado pikeminnow, humpback chub, and the razorback sucker, whose critical habitat includes the lower Gunnison River.