HYDROGEOLOGICAL CHARACTERIZATION OF SPRINGS OF THE HARNEY BASIN, OREGON

Semi-arid regions across the globe are experiencing increased groundwater use due to vastly expanded irrigation and variable water supplies under prolonged drought conditions. This can lead to a variety of water quality and quantity issues such as irreversible lowering of the water table, increased contaminant load, and in extreme circumstances ground subsidence.

Springs discharge groundwater to the land surface allowing for direct study of subsurface hydrogeological processes, and are an important source of surface water in semi-arid environments. The Harney Basin is a 3800 km² endorheic basin located in semi-arid southeastern Oregon where spring discharge has decreased notably in recent years. We present new measurements of spring chemistry, including stable isotopes of water, major anions and cations, and trace metals. Using the new data and a comprehensive catalog of physical and chemical measurements of water from wells, surface waters, and spring waters, we identify and better constrain recharge areas and basin-scale groundwater flowpaths.

Groundwater is a crucial resource in regions with increasingly variable water supplies, but there is a critical lack of knowledge on these resources and how they are used. Despite broad heterogeneity in the hydrogeological nature of aquifer systems worldwide, examining local-scale systems such as the Harney Basin provide valuable characterizations that may be adapted to other groundwater systems.