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Scientific Investigations Report 2005-5280

Geologic, Hydrologic, and Chemical Data from the C Aquifer near Leupp, Arizona

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Prepared in cooperation with the

By J.P. Hoffmann, D.J. Bills, J.V. Phillips, and K.J. Halford



As the most productive aquifer in northern Arizona, the C aquifer provides industry, land owners, businesses, and municipalities with a dependable supply of water. Because additional development is proposed, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, conducted an investigation of the C aquifer that included the collection of geologic, hydrologic, and water-chemistry data near Leupp, Arizona. The investigation included a program to drill test wells at three sites and use the wells to collect geologic and geophysical logs, collect and analyze aquifer-test data, and collect water samples for water-chemistry analyses. Rock units penetrated during drilling were, in descending order, the Moenkopi, Kaibab, and Toroweap Formations, the Coconino Sandstone, the Schnebly Hill Formation, and the Upper Supai Formation. The water table generally was within the Coconino Sandstone and ranged from about 226 to 615 feet below land surface. Constant-rate aquifer test were simulated by using numerical models to estimate aquifer properties. Estimated transmissivity of the C aquifer near Leupp, Arizona, ranges from about 5,400 to 7,000 feet squared per day. The Coconino Sandstone is the most conductive unit of the aquifer.

Water quality, determined from samples collected during the constant-rate aquifer tests, is generally good for intended uses. Field specific-conductance values ranged from 837 to 1,230 microsiemens per centimeter and correlate with concentrations of dissolved chloride and sodium. Concentrations of arsenic and other trace metals, as well as concentrations of nutrients, were low. Concentrations of sulfate exceeded the U.S. Environmental Protection Agency Secondary Maximum Contaminant Level of 250 milligrams per liter at all sites and were highest at site 1 (about 385 milligrams per liter). Gross alpha and gross beta activity in ground water provide evidence the water had been exposed to radioactive material, such as uranium. Oxygen and hydrogen isotopic ratios in the ground water indicate the water was recharged at altitudes of about 6,700 to 7,600 feet.


Drilling, Well Construction, and Static Water-Level Information
Geologic Logs
Aquifer-Test Analysis
Water Chemistry
References Cited

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