MOUNTAIN SPRING CONTROLS ON STREAM WATER QUALITY AND QUANTITY IN THE NON-PERENNIAL GIBSON JACK WATERSHED IN SOUTHEASTERN IDAHO

Natural springs represent an important transition between surface and subsurface flows, and in the semi-arid mountain west, springs’ sensitivity to climate change remains uncertain. For example, resilient springs may serve as climate refugia, sustaining cold-water flows during drought whereas sensitive springs may experience flow loss, leading previously perennial streams to dry. To assess how recent variations in spring water quantity and quality affect flows in a non-perennial stream network, we focused on the Gibson Jack watershed in southeastern Idaho, where 30 springs have been identified. To understand stream sources and spring water quality, we sampled for water isotopes and we measured discharge, temperature and specific conductance at the point of emergence of the springs. Preliminary results suggest that spring discharge contributes 12-37% of total watershed discharge and varies seasonally rather than remaining stable throughout the seasonal recession. Spring discharge decreases seasonally by 33-95% even though isotopes reveal that spring water is consistently derived from snow. As the snowfall fraction decreases, springs may thus be disproportionately impacted, implying that non-perennial stream networks may become both warmer and drier.