The Navajo Aquifer (N-aquifer) lies beneath the Black Mesa plateau and the Hopi and Navajo reservations.
The N-aquifer is the most significant source of water in the region and is the only aquifer in the area that naturally meets the EPA's standards for drinking water. Concentrations of total dissolved solids (TDS) in unfiltered N-aquifer water are generally less than 400 milligrams per liter (mg/l). The EPA's standard for drinking water is 500 mg/1.
Water from the N-aquifer feeds springs in the area which are essential to the religious practices of members of the Hopi Tribe.
Peabody Energy, which is the largest private coal producer in the world, operates two strip mines on Black Mesa, the Kayenta and Black Mesa mines. Collectively, these mines constitute the most extensive strip mine operation in the United States. During fiscal year 1998, Peabody removed just under 11.8 million tons of coal from its Arizona mines. Coal from the Black Mesa mine is used to power the Mohave Generating Station in Laughlin, Nevada.
In order to transport its coal from Black Mesa to Laughlin, Peabody mixes it with water (creating "slurry") and pipes the coal in liquid form. Peabody withdraws over 4,000 acre-feet of water from the N-aquifer per year to fuel its slurry operation. One acre-foot of water is equal to 325,851 gallons, enough liquid to fill a football field one foot deep. Four thousand acre-feet comes to more than 1.3 billion gallons of water per year. Put another way, the pipeline consumes an average of 120,000 gallons of water per hour, with 43,000 tons of coal slurried per day.
According to documents filed with the EPA, the Black Mesa pipeline failed 12 times between 1994 and 1999, and at least eight of those failures resulted in discharges of coal or coal slurry into local washes.
The Natural Resource Defense Council’s report "Drawdown: Groundwater Mining on Black Mesa" reviewed data reported by the U.S. Geological Survey and the Office of Surface Mining.
NRDC's report shows that:
• water levels have decreased by more than 100 feet in some N-aquifer wells;
• discharge has dropped by more than 50% in the majority of monitored N-aquifer springs;
• some localized contamination of the aquifer may be taking place;
• the federal government has a "trust duty" which obligates it to protect the N-aquifer; and
• the hydrologic models the government uses to monitor the aquifer are outdated and incomplete.
NRDC's review indicates that at least one of the government's four criteria that are used to asses when "material damage" to the N-aquifer has occurred (known as the "CHIA" criteria) has already been exceeded. Further, data suggest that at least two more criteria may have been surpassed.
NRDC recommends the following steps be taken to preserve the N-aquifer:
• Peabody should cease groundwater pumping from the N-aquifer no later than 2005;
• Peabody should immediately implement an N-aquifer use-reduction plan,
• the Interior Department should complete the three-part study of coal transport alternatives that it began in the early l990s;
• the Department of Interior should recalibrate its model and improve its monitoring of the N-aquifer;
• though implementing one or more effective, environmentally sensitive alternatives, the Department of the Interior should ensure a viable, stable long-term supply of water for the Hopi and Navajo reservations;
• the Department of the Interior should adopt "safe yield" as its management goal for Black Mesa;
• with tribal consent, the Environmental Protection Agency should designate the N-aquifer a "sole source aquifer" pursuant to the Federal Sole Source Aquifer Protection Program; and
• tribal sovereignty must be respected, and federal and tribal governments should work cooperatively to manage aquifer resources.
