4.3 Chemical and isotopic composition
As the snowpack started to melt in the catchment in late May 2019, the alkalinity at GS1 briefly fell, and spring water became depleted in deuterium (Figure 8E). This suggests the contribution of snowmelt water to the springs through infiltration, as water levels were rising (Figure 8B). However, once water levels reached a maximum in the lake on June 4, spring temperature and alkalinity began to increase, and isotopic compositions became less negative (Figure 8D). This could be due to the increased hydraulic gradients forcing pre-melt groundwater out at the springs. After July 10, alkalinity decreased with falling water levels (Figure 8).
Water samples were collected in the three spring branches and on the north shore of Hathataga Lake between August 7 and 14, 2019; and analyzed for alkalinity and major ions (Figure 9). The lake had an alkalinity of 1.8 meq L‑1, which was most similar to S1, the warmest spring branch, and most dissimilar to S3, the coldest spring branch.