GROUNDWATER RECHARGE BY GLACIAL LAKES IN THE WASATCH RANGE AND UINTA MOUNTAINS, UTAH

The conventional wisdom has long been that groundwater in Salt Lake and Utah Valleys is recharged by losing streams from the Wasatch Range. However, recent work using noble gases has shown that much of the groundwater in Salt Lake and Utah Valleys follows subterranean flow paths from the Wasatch Range. The objective of this study was to calculate the groundwater recharge by individual glacial lakes in the Wasatch Range and Uinta Mountains by measuring the input and output stream discharges, estimating lake evaporation from the difference between lake and input stream electrical conductivities, and measuring the lake level between two visits roughly two weeks apart. In the Wasatch Range, groundwater recharge was calculated for Lake Blanche, Lake Florence, White Pine Lake, Lower Red Pine Lake, Upper Red Pine Lake and Silver Lake as 7.9 × 10⁴ m³/month, 4.5 × 10³ m³/month, 7.4 × 10⁴ m³/month, 5.7 × 10⁵ m³/month, 4.7 × 10⁵ m³/month, and 7.0 × 10⁵ m³/month, respectively, while Lake Lillian had a groundwater discharge of 4.7 × 10⁴ m³/month. In the Uinta Mountains groundwater recharge was calculated for Amethyst Lake, McPheeter Lake and BR-24 Lake as 3.3 × 10⁶ m³/month, 2.1 × 10⁴ m³/month, and 2.07 × 10⁴ m³/month, respectively, while Ryder Lake had a groundwater discharge of 6.6 × 10³ m³/month. The Wasatch Range lakes studied had a net groundwater recharge of 1.9 × 10⁶ m³/month. These lakes included about half the glacial lake surface area of the Wasatch Range, implying a total groundwater recharge of 3.8 × 10⁶ m³/month, which is consistent with Manning and Solomon’s (2003) range of (1.7 – 3.9) × 10⁶ m³/month based on noble gases. We are suggesting that almost all of the groundwater recharge from the Wasatch Range occurs through the glacial lakes. Moreover, very little of this groundwater recharge enters streams on the Wasatch Range (local flow), but nearly all appears as groundwater in Salt Lake and Utah Valleys (regional flow). Further research will include estimating each lake area’s drainage basin and annual precipitation for comparison with estimates of groundwater recharge, as well as more precise estimates of total glacial lake surface area and groundwater recharge. Further results will be reported at the meeting.