The total water discharge in Hot Creek Gorge is calculated using periodic measurements of stream discharge and the average concentrations of chloride and boron at sites upstream (HCA) and downstream (HCF) from the area where the hot springs discharge into the creek. The streamflow and chemical concentrations are multiplied together to produce values for chemical flux at both the upstream and downstream sites. The difference in flux between sites, divided by the concentration of Cl and B in the hot spring waters (220 mg/L and 10 mg/L, respectively) yields estimates of total thermal-water input.
Most of the short-term variability in the hot-spring discharge data results from the level of precision (+/- 10 percent) in measurements of streamflow, integrated sampling, and chemical analysis. Given this uncertainty, it is difficult to discern any actual changes in total thermal-water dicharge from 1988-1998. This is also true for the period of unrest in 1997. Visual observations did, however, show significant changes in flow of some hot-spring vents associated with seismic events in the south moat during the fall of 1997.
