Colowyo commenced surface mining in 1977 and has mined from four distinct pits during the life of the existing operation. The East Pit was the first pit opened and where mining concluded in 2006. Mining commenced in the Section 16 Pit in 1992 and continued until 2002. Mining in the Section 16 Pit was a single seam operation, whereas, the other pits at Colowyo have required the mining of multiple seams. Reclamation on a majority of the Section 16 Pit occurred from 1993 to 1998. The remaining acres of the Section 16 Pit that have not been reclaimed are supporting ongoing mining activities, and they will be reclaimed with the South Taylor Pit. Mining began in the West Pit in 1994 and mining was concluded in 2014. Currently, the West Pit is in various stages of reclamation. In 2008, Colowyo opened the South Taylor Pit and this pit is the current mining location. The South Taylor Pit has since produced on average approximately 2.3 mtpy of coal by utilizing truck/shovel, dragline and highwall mining techniques.

Historically and currently, coal is mined from the pits and hauled to a primary crusher. Once it is sized at the primary crusher it is then hauled along the existing haul road to the north northeast approximately 3.9 miles (6.3 km) to the Gossard Loadout. Once coal arrives at the Gossard Loadout it is sized accordingly again, and then loaded on a train for shipment.