Water in a Dry Land

By Bob Hart and Blake Thomas

The USGS hydrologists at the Flagstaff Science Center have been leaders in developing productive and beneficial tribal water-resource programs in Northern Arizona. During the past 17 years, water-resource programs have been developed with the Navajo Nation; the Hopi, Havasupai, Hualapai, and Yavapai-Prescott tribes; the Pueblo of Zuni; and the Kaibab Band of the Paiute Indians. The accomplishments include detailed hydrologic assessments of tribal water resources, installing water-resource monitoring networks for surface- and ground-water resources, and organizing numerous training opportunities for tribal employees. By helping tribal employees develop their technical capabilities, USGS is enabling tribes to improve management of their water resources. As a result, the USGS is seen as a leader in tribal programs.

Map delineating tribal lands in northern Arizona. Currently, the water office at the Flagstaff Field Center has cooperative agreements to monitor, analyze, or explore surface- and/or ground-water issues with all of these tribes.

The USGS is committed to providing data and information to Indian Tribes and to other DOI bureaus. An example of this type of work is the Black Mesa Monitoring Program in northern Arizona. It is only one of the numerous ongoing projects that demonstrate our commitment to working with local Tribal governments, private industry, and other Federal and State agencies. Using data collected from this project, the Office of Surface Mining facilitates oversight and regulation of the coal-mining operations of Peabody Western Coal Company on Tribal land. The long-term ground-water, surface-water, and water-quality data collected for this program provide an important opportunity to investigate and gain a better understanding of a hydrologic system of bedrock geology in an arid climate in which there are many competing water-use interests.

Landsat ETM+ false-color composite of the Black Mesa area in northeastern Arizona. Bands 7, 4, 2 are shown in red, green, and blue respectively.

The long-term availability of water in the Black Mesa area is critical to many parties, including the Hopi Tribe, Navajo Nation, and Peabody Western Coal Company. The hydrologic data collected in this monitoring program are needed to understand the available water supply and the effects of industrial and municipal ground-water withdrawals.

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. 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.

Annual withdrawals from the N aquifer for industrial and municipal use have increased from about 70 acre-ft in 1965, to 4,300 acre-ft in 1972, to 8,000 acre-ft in 2002. Members of the Navajo Nation and Hopi Tribe live in the Black Mesa area, and they depend on ground water from the N aquifer to meet municipal, domestic, livestock, and irrigation needs. In addition, the springs and streams fed by ground-water discharge are an important part of their cultures. Peabody Western Coal Company began operating a strip mine in the northern part of Black Mesa in 1968. The company withdraws water from the N aquifer for a slurry pipeline to transport coal to a powerplant in Laughlin, NV. Withdrawals by the company accounted for about 70 to 80 percent of the total withdrawals in the early and mid 1970's and have been about 60 percent of the total withdrawals from 1978 to 2002.

Gayl Honani, Hopi Tribe, collecting water at Pasture Canyon Spring, Black Mesa of northern Arizona.

The Navajo Nation and Hopi Tribe are concerned about the effect of this increasing pumpage on long-term water supply, discharge in streams and springs, and quality of ground water. This concern led to the establishment of a long-term program in 1971 to monitor ground-water levels, quality, discharge, and surface-water discharge. From the 1960's to 2002, water levels in the N aquifer declined by over 50 feet in 9 of 17 long-term monitoring wells in confined areas. No large changes have been detected in ground-water levels in unconfined areas, ground-water discharge, ground-water quality, or surface-water discharge.

Additional information and related sites dealing with research projects past and current can be found at http://wwwflag.wr.usgs.gov/USGSFlag/Water/water.html