Animal carcass disposal can have a negative impact upon water quality. If not done properly, carcass disposal can lead to pollution or contamination of water intended for domestic use. Carcasses should be disposed of within 24 hours. Options for disposal:

Idaho State Code includes laws pertaining to the disposal of animal carcasses. It is illegal in Idaho to leave the carcass of any animal within ¼ mile of any inhabited dwellings, public highways, or streams of water for more than 24 hours. If the exposure of or burial within 200 feet of these areas pollutes or contaminates water, a misdemeanor citation could be issued. Cremation of any animal carcass within ¼ mile of a city, town, or village is also a violation of the law. Finally, don't ever dispose of a carcass in water or on a publicly used road.

The Idaho State Department of Agriculture has more information on this topic.