3.3.1.7 Mineral and Geothermal Resources

and a few areas of boulders and large bedrock shards are located sporadically along the shoreline and extend into the water.

North Platte River

To facilitate access to the main access tunnel entrance for the Project, a bridge will be constructed north of Seminoe Dam across the North Platte River section close to Seminoe Dam. Substrate in this area is dominated by boulder with some scattered areas of cobble/rubble. The stream banks in this area are relatively steep, generally unvegetated, and dominated by boulders.

3.3.1.7 Mineral and Geothermal Resources

Wyoming is a national leader of energy production from coal, uranium, natural gas, and crude oil. Wyoming also has potential for the development of alternative forms of energy including geothermal. Wyoming’s geologic setting—along with ideal conditions of heat, pressure, and time—has led to the creation of large reservoirs of oil and natural gas within the strata of the state’s basins. Vast reserves of coal also underlie the state, and Wyoming has the largest uranium reserves in the U.S. (WSGS 2022a).

Wyoming has the world’s largest deposit of trona, a sodium carbonate compound that is processed into soda ash or baking soda. This mineral is Wyoming’s top export and is mined from the Green River Formation over 100 miles west of the Project (Wyoming Mining Association, 2022). Wyoming also produces more bentonite than any other state. Bentonite is mined from surface deposits in the northern parts of the state. No trona or bentonite is produced in the vicinity of the Project (Wyoming Mining Association, 2022).

Oil and Natural Gas

Coal, oil, and natural gas all exist within Wyoming and the Project vicinity (BLM 2008a). Wyoming’s first oil well was drilled in 1884 and its first refinery was built in Casper in 1895 (WSGS 2022d). Gas production began as early as 1974 and production has fluctuated over time. Most gas exploration has occurred in the eastern Greater Green River Basin, including the Great Divide Basin, and wells are targeted for stratigraphic traps in rocks of the Upper Cretaceous. There has also been drilling in the rocks of the Precambrian in the area. Exploration for gas reserves in coalbeds has occurred to the west of the Project vicinity and in the Hanna Basin, just to the east of the Project vicinity (BLM 2008a).

Coal

Wyoming is one of the top coal-producing states in the U.S. (Webster and McNamee 2019). Most coal occurs in rock sequences deposited during the Cretaceous Period and Paleocene and Eocene Epochs when the climate was warm and humid and suitable for vegetation growth in brackish/freshwater swamps (WSGS 2020). Commercial mining of coal in Wyoming began in the mid-1860s. At one time (pre-1920) coal was the most valuable mineral resource, but it now ranks behind petroleum and natural gas. There are significant oil shale reserves in the southwest of the state. In the area immediately surrounding the Project vicinity, there are six coalfields containing coal resources of subbituminous to bituminous rank (Hanna Basin, Carbon Basin, Great Divide Basin, Rock