Selected hydrologic data for the central Virgin River basin area, Washington and Iron Counties, Utah, 1915-97

Abstract

Hydrologic data were collected in Washington and Iron Counties, Utah, from 1995 to 1997 to better understand the hydrologic system. Data from earlier years also are presented. Data collected from wells include well-completion data, water-level measurements, and physical properties of the water. Data collected from springs and surface-water sites include discharge and physical properties of the water. Selected water samples collected from ground-and surface-water sites were analyzed for isotopes, chlorofluorocarbons, and dissolved gases. INTRODUCTION This report contains hydrologic data collected in Washington and Iron Counties, Utah, from 1995 to 1997, as well as data from earlier years. The study area is in the southwestern corner of Utah and includes all of Washington County west of the Hurricane Fault and the southern part of Iron County. The area is about 1,900 ry mi and includes both the Basin and Range and the Colorado Plateau physiographic provinces described by Fenneman (1931). Population in this area has increased by more than 160 percent from 1980 through 1995 (Utah State Data Center, 1991, 1997). Both full-time and winter residents are attracted to the area, known as "Utah's Dixie," because the climate is warmer there than in the rest of the State. The greatest challenge to further growth is the limited water resources because the climate is so dry. The largest constraint on development of additional residential areas and commercial activities is water supply. Surface water in the area drains from the central Virgin River drainage basin and is fully appropriated. The need for increased groundwater withdrawals prompted the Utah Department of Natural Resources, Division of Water Rights, to initiate a 4-year study of the groundwater resources of the area in cooperation with the U.S. Geological Survey and the Washington County Water Conservancy District. Data were collected to better understand the hydrologic system in the area and to assess the effects of increased groundwater withdrawals on groundwater levels, discharge from springs, surface-water flows, and water quality. This report documents hydrologic data collected as part of the central Virgin River basin area groundwater study. Groundwater data were collected from existing wells and springs and from new wells completed by private owners, developments, and municipalities during 1995-97. For comparison, this report also provides data from earlier years, some of which were published previously by Cordova (1972, 1978) and Budding and Sommer (1986).

Innovative Environmental Tracer Techniques for Evaluating Sources of Spring Discharge from a Carbonate Aquifer Bisected by a River

“…The trilinear diagram (Figure ) shows two potential end‐member waters in the Virgin River Gorge subarea: (1) Virgin River samples collected at VR‐8 and VR‐11 upstream of Littlefield Springs, and (2) a synthetic composite representing the carbonate aquifer. This composite was based on samples from the McCullough Well (MCW) completed in the Permian Kaibab Formation about 30 km east of the study area (Wilkowske and Heilweil ), Blue Point Spring (BPS) and Rogers Spring (RGS) discharging from gypsiferous carbonates near Lake Mead about 60 km southwest of the study area (Hershey et al ), and Lost Spring (LST) discharging from the Permian Kaibab Formation in the Virgin Mountains (this report; Figure ). LST is considered a carbonate‐aquifer end member for major and trace‐ion geochemistry, but not for age or recharge conditions since it is located south of the springs rather than receiving water from the primary recharge area in the northern part of the study area.…”