Bedrock aquifers of eastern San Juan County, Utah

Charles Avery

doi:10.3133/ofr85568

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Bedrock aquifers of eastern San Juan County, Utah

Charles Avery

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Abstract

This study is one of a series of studies appraising the water-bearing properties of the Navajo Sandstone and associated formations in southern Utah. The study area is about 4,600 square miles, extending from the Utah-Arizona State line northward to the San Juan-Grand County line and westward from the Utah-Colorado State line to the longitude of about 109°50'. Some of the water-yielding formations are grouped into aquifer systems. The C aquifer is comprised of the DeChelly Sandstone Member of the Cutler Formation. The P aquifer is comprised of the Cedar Mesa Member of the Cutler Formation and the undifferentiated Cutler Formation. The N aquifer is comprised of the sedimentary section that includes the Wingate Sandstone, Kayenta Formation, Navajo Sandstone, Carmel Formation, and Entrada Sandstone. The M aquifer is comprised of the Bluff Sandstone Member and other sandstone units of the Morrison Formation. The D aquifer is comprised of the Burro Canyon Formation and Dakota Sandstone. Discharge from the ground-water reservoir to the San Juan River between gaging stations at Four Corners and Mexican Hat is about 66 cubic feet per second. The N aquifer is the main aquifer in the study area. Recharge by infiltration of precipitation is estimated to be 25,000 acre-feet per year. A major ground-water divide exists under the broad area east of Monticello. The thickness of the N aquifer, where the sedimentary section is fully preserved and saturated, generally is 750 to 1,250 feet. Hydraulic-conductivity values obtained from aquifer tests range from 0.02 to 0.34 foot per day. The total volume of water in transient storage is about 11 million acre-feet. Well discharge somewhat exceeded 2,340 acre-feet during 1981. Discharge to the San Juan River from the N aquifer is estimated to be 6.9 cubic feet per second. Water quality ranges from a calcium bicarbonate to sodium chloride type water.

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Source-reported bounding extent: 36.997968° to 42.001567° latitude; -114.052962° to -109.041058° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeX RIS

Charles Avery. 1985. Bedrock aquifers of eastern San Juan County, Utah. https://doi.org/10.3133/ofr85568

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