CHARACTERIZATION OF GROUNDWATER RESOURCES IN SANPETE VALLEY, UTAH: MODERN SURVEY OF A CHANGING HYDROLOGIC SYSTEM

Local water users, regional development authorities, and the State Engineer’s Office have identified a need for an updated assessment of the principal valley-fill aquifer in Sanpete Valley, Utah. Previous groundwater budgets were calculated in the 1960s and 1980s. Since then, significant changes have occurred in the watershed including extended periods of drought, conversion from flood to pressurized irrigation systems, increased groundwater pumping in lieu of surface water diversions, and growing demand for culinary water. Anecdotal reports suggest these changes have led to lower groundwater levels, decreased spring and artesian well discharge, and drying of lowland meadows.

Throughout 2024, the UGS conducted a comprehensive field campaign in Sanpete Valley, combining traditional and modern methods to characterize the hydrologic system. Following historical protocols, we measured groundwater elevations in March and November, took discharge measurements on all San Pitch River tributaries during high water and baseflow, and sampled a representative range of springs and seeps. When possible, we revisited sites measured in earlier reports. To better constrain aquifer recharge, we conducted seepage runs on major tributaries to address a data gap in previous work. We also employed tools that were not readily available during earlier studies such as stable isotopes to fingerprint water sources and estimate mixing, and remote sensing to map distribution of precipitation and evapotranspiration.

Results of this study quantify changes in the Sanpete Valley aquifer over the past several decades and improve our understanding of groundwater-surface water interactions in the region. We established a new hydrogeologic baseline that can be used to assess changes in wells, springs, streams, and wetlands and provide recommendations that can be used to create a long-term monitoring program. This information will help stakeholders address challenges like drought resiliency, water right change applications, and future population growth.