The award was presented to Thunder Basin's Black Thunder and Coal Creek mines.
"The Black Thunder and Coal Creek personnel take pride in the amount of wildlife they have on their minesites," Wyoming Department of Environmental Quality land quality division permit coordinator Stacy Page said.
"They are conscientious about creating wildlife habitat with diverse vegetation, nesting platforms and amenities for the water fowl around and in many of their ponds."
Arch executives were in town to receive the award.
“We're proud of the extraordinary efforts the employees of Thunder Basin have taken to protect wildlife on mine property," Arch Coal executive vice-president and chief operating officer Paul A Lang said.
"One of the ways Thunder Basin exhibits our strong commitment to neighbourly practices is through such innovative mine reclamation efforts."