36 The Geology of State and National Parks of Utah and the Rocky Mountain Region

Tuesday, 20 May 2025
10:15 AM - 12:00 PM
Cascade C

WATER QUALITY AND WATER BUDGET OF THE VALLEY-FILL AQUIFER NEAR BRYCE CANYON NATIONAL PARK, GARFIELD COUNTY, UTAH

Paper number: 36-1
Program: Theme Sessions
Time: 10:15 AM – 10:30 AM

Authors

Abstract

Bryce Canyon National Park relies partly on water resources in the nearby aquifers of Emery and Johns Valleys in southern Utah. The town of Bryce Canyon City is an area of active tourism and, therefore, increased growth (likely hotel development). Increased demand for drinking water warrants careful land-use planning and resource management to preserve the valley-fill aquifer’s surface and groundwater resources. We investigated the area to characterize the hydrogeology of the valley-fill aquifer as it pertains to the occurrence and flow of groundwater, with emphasis on characterizing groundwater quality, flow paths, quantity, and connection to surface water, principally the East Fork Sevier River.

We measured water levels and sampled water during autumn and spring from 2018 to 2021 in selected wells, springs, and streams. We measured discharge in streams, springs, and canals in the East Fork Sevier drainage system over 2 seasons and 4 years.

Most development is on unconsolidated valley-fill deposits, the primary source of groundwater. Data show overall pristine water quality (average total-dissolved-solids concentration of 304 mg/L) and fluctuating water levels in wells, with marked increase in water levels in wells after heavier precipitation years. Wells completed in alluvium generally show a water level rise during spring 2019, 2021, and 2023; water levels in bedrock wells dropped or remained unchanged during all seasonal measurement campaigns.

Using a soil-water-balance model, we estimated average values of discharge and recharge to the valley-fill aquifer of ~11,000 ac-ft/yr and ~9200 ac-ft/yr for 2017 to 2021, respectively. We used historical well hydrograph data (1946–2019) to show overall long-term water level change is around zero, indicating long-term change in storage is negligible compared to our study’s short-term average change of an almost 2000 ac-ft/yr deficit. With continued drought in the desert Southwest, we recommend careful planning of this limited resource and preservation of its excellent water quality.

Geological Society of America Abstracts with Programs. Vol. 57, No. 5

doi: 10.1130/abs/2025RM-409493

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