An evaluation of the water resources of the Zuni Tribal lands in west-central New Mexico was made to determine the yield, variability, and quality of water available to the Pueblo of Zuni. This study is needed to aid in orderly development of these resources.

Rocks of Permian to Quaternary age supply stock, irrigation, and domestic water to the Zuni Indians. The Glorieta Sandstone and San Andres Limestone (Glorieta-San Andres aquifer) of Permian age and sandstones in the Chinle Formation of Triassic age provide most of this water supply.

Water in the Glorieta-San Andres aquifer is confined by minimal-permeability shales and is transmitted through the aquifer along interconnected solution channels and fractures. Water-level and water-quality information indicate greater hydraulic conductivities along the southern boundaries of Zuni Tribal lands.

Well yields from the Glorieta-San Andres aquifer are as much as 150 gallons per minute and aquifer transmissivity ranges from 30 to 1,400 feet squared per day. Long-term, water-level declines of as much as 29 feet have been measured near pumping centers at Black Rock. Multiple-well aquifer tests are needed to further define aquifer properties (storage, transmissivity, and leakage from confining units) and the effects of well design on well yields. Dissolved-solids concentrations in water from the aquifer ranged from 331 to 1,068 milligrams per liter. Calcium and sulfate are the predominant ions.

Water in sandstones of the Chinle Formation is confined by adjacent shales and is transmitted along interconnected fractures. Well yields range from 5 to 125 gallons per minute and aquifer transmissivity ranges from 40 to 1,400 feet squared per day. Water-level declines of as much as 27 feet have been measured near Zuni Village. Dissolved-solids concentrations in water from the aquifer ranged from 215 to 1,980 milligrams per liter. Sodium and bicarbonate are the predominant ions.

Other sources of ground water are used primarily for livestock watering by means of windmills, with the exception of buried alluvial channel deposits along the Rio Pescado. These deposits provide domestic and irrigation water through springs and wells to Pescado and Black Rock.

The Bidahochi Formation of Miocene and Pliocene age could potentially provide an additional supply of water chemically suitable for most uses. Seismic-reflection techniques are being used to locate buried channels eroded in the rocks underlying the Bidahochi Formation. These buried channels may contain thicker sections of saturated sands and gravels that could be developed for stock and domestic use.