Research about Juab Valley

USGS1999

Simulation of ground-water system response to proposed withdrawals from 1993 to 2043 in the northern part of Juab Valley, Juab County, Utah

Information on the ground-water system in the northern part of Juab Valley, Utah, is needed by water managers to plan the optimal use of surface water that will be imported by the Central Utah Project and ground water pumped locally. The response of the ground-water system to an increase in withdrawal with no new sources of recharge was simulated to provide a baseline for comparing possible water-management plans and to determine their potential effects on wetlands in the area. To assess the effects of additional withdrawal on the system, a 50-year-long stress period was added to the end of the existing three-dimensional, finite-difference, ground-water flow model. This stress period simulates recharge and discharge stresses determined for 1987-92. Another model was constructed by simulating 30 additional wells pumping a total of 4,000 acre-feet per year in the 50-year-long stress period. The 30 additional wells were simulated in a north-south trending line along the eastern part of the valley and as pumping from the bottom model layer. The difference between model-computed water-level changes after 10, 30, and 50 years with and without the additional pumped wells was calculated for the uppermost model layer. Water-level declines of more than 6 feet were computed for layer 1 in the area east of Mona Reservoir, and natural sources of ground-water discharge in the northern part of the valley decreased in response to 30 years of additional pumping. Discharge from springs and seeps computed in 2022 of the revised model simulating additional pumping decreased by about 7 percent and computed discharge by evapotranspiration decreased by about 23 percent relative to the same time in the revised model simulating no additional pumping.

Utah↗

USGS1996

Hydrology and simulation of ground-water flow in Juab Valley, Juab County, Utah.

Plans to import water to Juab Valley, Utah, primarily for irrigation, are part of the Central Utah Project. A better understanding of the hydrology of the valley is needed to help manage the water resources and to develop conjunctive-use plans. The saturated unconsolidated basin-fill deposits form the ground-water system in Juab Valley. Recharge is by seepage from streams, unconsumed irrigation water, and distribution systems; infiltration of precipitation; and subsurface inflow from consolidated rocks that surround the valley. Discharge is by wells, springs, seeps, evapotranspiration, and subsurface outflow to consolidated rocks. Ground-water pumpage is used to supplement surface water for irrigation in most of the valley and has altered the direction of groundwater flow from that of pre-ground-water development time in areas near and in Nephi and Levan. Greater-than-average precipitation during 1980-87 corresponds with a rise in water levels measured in most wells in the valley and the highest water level measured in some wells. Less-than average precipitation during 1988-91 corresponds with a decline in water levels measured during 1988-93 in most wells. Geochemical analyses indicate that the sources of dissolved ions in water sampled from the southern part of the valley are the Arapien Shale, evaporite deposits that occur in the unconsolidated basin-fill deposits, and possibly residual sea water that has undergone evaporation in unconsolidated basin-fill deposits in selected areas. Water discharging from a spring at Burriston Ponds is a mixture of about 70 percent ground water from a hypothesized flow path that extends downgradient from where Salt Creek enters Juab Valley and 30 percent from a hypothesized flow path from the base of the southern Wasatch Range. The ground-water system of Juab Valley was simulated by using the U.S. Geological Survey modular, three-dimensional, finite-difference, ground-water flow model. The numerical model was calibrated to simulate the steady-state conditions of 1949, multi-year transient-state conditions during 1949-92, and seasonal transient-state conditions during 1992-94. Calibration parameters were adjusted until model-computed water levels reasonably matched measured water levels. Parameters important to the calibration process include horizontal hydraulic conductivity, transmissivity, and the spatial distribution and amount of recharge from subsurface inflow and seepage from ephemeral streams to the east side of Juab Valley.

Utah↗