Research about Coconino aquifer

USGS2025

Assessment of water chemistry of the Coconino aquifer in northeastern Arizona

The Coconino aquifer was investigated as a potential groundwater resource for the Hopi Tribe and Navajo Nation in northeastern Arizona. Basic groundwater chemistry, including major ions, total dissolved solids, and selected trace metal concentrations, are presented and analyzed to characterize the Coconino aquifer. The geochemical compositions of groundwater are associated with changes in geology and groundwater movement and are compared to drinking-water standards to determine suitable areas for potential groundwater resource development. Dissolved-solids concentrations in much of the Coconino aquifer water were higher than the U.S. Environmental Protection Agency’s secondary drinking-water standard of 500 milligrams per liter (mg/L) due to a buried halite body in the southeastern part of the study area. However, trace metal concentrations were generally low. Groundwater may need to be treated for high dissolved-solids concentrations before it is suitable for use as a resource for the Hopi Tribe and Navajo Nation.

Arizona↗

USGS1979

Water budget and mathematical model of the Coconino Aquifer, southern Navajo County, Arizona

The main source of water in the 3,400-square-mile area of southern Navajo County is the large volume of ground water in storage in the Coconino aquifer, which consists of the Coconino Sandstone, the uppermost part of the underlying Supai Formation, and the overlying Kaibab Limestone. The amount of water withdrawn from the aquifer increased from about 13,800 acre-feet in 1960 to 38,400 acre-feet in 1972. As industrial and agricultural development continues, the amount of withdrawal probably will increase greatly. Aquifer tests indicate that the hydraulic conductivity of the aquifer ranges from 8 to 40 feet per day; however, a flow-net analysis indicates that the hydraulic conductivity may be as much as 80 feet per day in the north-central part of the area. In the southern and central parts of the area the aquifer is unconfined, and the storage coefficient is estimated to be about 0.15. In the northern and eastern parts the aquifer is confined, and the storage coefficient ranges from 0.00013 to 0.0014. A mathematical model was developed to simulate the groundwater system and to provide a management tool for estimating the effects of present and future ground-water withdrawals. The model indicates that the inflow to and outflow from the aquifer were about 105,600 acre-feet in 1960 prior to extensive ground-water development and that about 192,000 acre-feet of water was derived from groundwater storage between 1960 and 1972. The mathematical model provides an approximation of the Coconino aquifer and can be used to estimate the future response of the aquifer.

Arizona↗