![]() The N aquifer is approximately 1,000 feet thick. Stratigraphic section showing rock formations and hydrogeologic units of the Black Mesa area, northeastern Arizona (not to scale). The mine will continue to use a small quantity of water during the reclamation process. In August 2019, coal mining operations at the Black Mesa Complex ceased due to the planned closure of the Navajo Generating Station which was permanently closed in November 2019. From 2006 through 2018 Peabody’s water use only accounted for about 30 percent of the total water use and municipal users accounted for 70 percent of the water use. Withdrawals by Peabody Energy had accounted for about 70-75 percent of the total withdrawals to the mid-1980's and were about 60 percent of the total withdrawals from the mid-1980's to 2005. On January 1, 2006, Peabody Energy discontinued use of the coal slurry pipeline, which in turn reduced industrial water use by about 70 percent. Annual withdrawals from the N aquifer for industrial and municipal use increased from about 70 acre-ft in 1965, to 7,330 acre-ft in 2005. Peabody Energy began operating a strip mine in the northern part of Black Mesa in 1968 and used N aquifer water to slurry coal 273 miles away to an electric power plant in Laughlin, Nevada. ![]() Location of Black Mesa study area, northeastern Arizona The monitoring program includes measuring potential recovery in the N aquifer as a result of the reduction in industrial pumpage by Peabody Western Coal Company. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This concern led to the establishment of a long-term program to monitor groundwater levels, groundwater discharge, groundwater quality, and surface-water discharge. The U.S. The Navajo Nation and Hopi Tribe have been concerned about the effects of pumping on long-term water supply, discharge in streams and springs, and quality of groundwater. ![]() The aquifer consists of three rock formations-the Navajo Sandstone, Kayenta Formation, and Wingate Sandstone, which are hydraulically connected and function as a single aquifer. The N aquifer is the major source of water for industrial and municipal users in the 5,400 square-mile Black Mesa area of northeastern Arizona. In addition, the springs and streams fed by groundwater discharge are an important part of their culture. The Navajo Nation and Hopi Tribe live in the Black Mesa area, and they depend on groundwater from the N aquifer to meet municipal, domestic, livestock, and irrigation needs.
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