Temperature Profiles of Groundwater Monitor Wells in Western Juab and Millard Counties, Utah

Abstract

The Utah Geological Survey (UGS) established a network of 68 groundwater monitoring wells at 27 well sites in several western Utah valleys, primarily in Millard and Juab Counties, from 2007 through 2009. In support of the UGS Snake Valley groundwater monitoring project, temperature logs were acquired from wells at 23 of these monitoring well sites using high-precision temperature logging gear. Wells were completed in a variety of geologic formations to test groundwater conditions within a Pliocene-Pleistocene basin-fill aquifer and a deep carbonate-rock aquifer consisting mainly of fractured Paleozoic limestone and dolomite strata. Well depths ranged from 67 ft (20 m) at Fish Springs to 1840 ft (561 m) near the community of Garrison. Bottom-hole temperatures ranged from about 53°F (12°C) in a shallow, 180-ft (55 m) well completed in valley-fill deposits near Needle Point Spring on the south end of Snake Valley, to 117°F (47°C) measured in a 1000-ft (305-m) deep well on the northwest side of the Middle Range (Juab County), completed in the Devonian Guillmette Formation. Thermal gradients range from near zero (isothermal conditions) at the well site near Garrison (UGS PW03) to a high of 6.72°F/100 ft (122.5°C/ km) at the well site northwest of the Middle Range (UGS PW18).