From The Pueblo Chieftain (Chris Woodka):
Trout Unlimited will sponsor the Second Annual Frostbite Fish-Off Jan. 20-21 and is looking to expand the reputation of the Arkansas River through Pueblo as a winter fishery.
The river is stocked with fish and negotiated flow programs are aimed at maintaining minimal flows throughout the winter. Typically warmer temperatures than other parts of the state and ease of access make Pueblo a mecca for winter fishing.
More Arkansas River basin coverage here.