Estimating groundwater inflow and leakage outflow for an intermontane lake with a structurally complex geology: Georgetown Lake in Montana, USA

Abstract

Stable isotopes of the water molecule (δ 18 O and δD) for groundwater, lake water, streams, and precipitation were coupled with physical flux measurements to investigate groundwater-lake interactions and to establish a water balance for a structurally complex lake. Georgetown Lake, a shallow high-latitude high-elevation lake, is located in southwestern Montana, USA. The lake is situated between two mountain ranges with highlands primarily to the east and south of the lake and a lower valley to the west. An annual water balance and (δ 18 O and δD) isotope balance were used to quantify annual groundwater inflows of 2.5 × 10 7 m 3 /year and lake leakage outflows of 1.6 × 10 7 m 3 /year. Roughly, 57% of total inflow to the lake is from groundwater, and 37% of total outflow at Georgetown Lake is groundwater. Stable isotopes of groundwater and springs around the lake and surrounding region show that the east side of the lake contains meteoric water recharged annually from higher mountain sources, and groundwater discharge to the lake occurs through this region. However, springs located in the lower western valley and some of the surrounding domestic wells west of the lake show isotopic enrichment indicative of strong to moderate evaporation similar to Georgetown Lake water. This indicates that some outflowing lake water recharges groundwater through the underlying west-dipping bedrock in the region.

Characterization of seasonal groundwater origin and evolution processes in a geologically heterogeneous catchment using geophysical, isotopic and hydro‐chemical techniques (Lough Gur, Ireland)

“…The lower d‐excess value of SW‐2 (creamery spring) illustrates the greater evaporative influence from lake water in comparison to the higher d‐excess values of SW‐3 (field spring) indicative of more rapid infiltration with less evaporative losses (Gautam et al, 2018). Similar d‐excess values exist between SW‐4 (sinkhole) and the bottom‐waters at the PZ‐2 piezometer nest suggesting efficient lake water mixing with a similar evaporative influence (Shaw et al, 2017).…”

“…and the bottom-waters at the PZ-2 piezometer nest suggesting efficient lake water mixing with a similar evaporative influence (Shaw et al, 2017).…”

Decreasing Groundwater Supply Can Exacerbate Lake Warming and Trigger Algal Blooms

“…On the other hand, changes in the magnitude of groundwater discharge to lakes can cause severe environmental impacts on groundwater‐dependent ecosystems. Since the dynamics of algal growth depends on nutrient availability, nutrient‐enriched groundwater discharging to the lake can have significant impact on nutrient‐algal dynamics (Essaid et al., 2020; Shaw et al., 2017). Moreover, groundwater flow with contamination by sewage water to lakes is identified as the primary cause of coastal eutrophication (Timoshkin et al., 2018).…”

Dual effects of precipitation and evaporation on lake water stable isotope composition in the monsoon region

“…The stable isotopic composition of lake water and its variations can be used to estimate components of the water budget, such as lake evaporation (Brooks et al, ; Mayr et al, ), leakage, and groundwater inflow (Shaw, Mitchell, & Gammons, ), which are difficult to monitor with traditional methods, and they can also elucidate the relationship between the transformation and replenishment of different water bodies (Ma & Edmunds, ; Zhan et al, ). In addition, the contribution ratio of evaporated water vapour to local atmospheric water vapour can be calculated using water balance and water isotope balance equations (Gat, Bowser, & Kendall, ).…”

“…The stable isotopic composition of lake water and its variations can be used to estimate components of the water budget, such as lake evaporation (Brooks et al, 2014;Mayr et al, 2007), leakage, and groundwater inflow (Shaw, Mitchell, & Gammons, 2017), which are difficult to monitor with traditional methods, and they can also elucidate the relationship between the transformation and replenishment of different water bodies (Ma & Edmunds, 2006;Zhan et al, 2016).…”