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Calculating salt loads to Great Salt Lake and the associated uncertainties for water year 2013; updating a 48year old standard

Shope, Christopher L., Angeroth, Cory E.
The Science of the total environment 2015 v.536 pp. 391-405
confidence interval, lakes, models, monitoring, regression analysis, surface water, total dissolved solids, uncertainty, Great Salt Lake
Effective management of surface waters requires a robust understanding of spatiotemporal constituent loadings from upstream sources and the uncertainty associated with these estimates. We compared the total dissolved solids loading into the Great Salt Lake (GSL) for water year 2013 with estimates of previously sampled periods in the early 1960s. We also provide updated results on GSL loading, quantitatively bounded by sampling uncertainties, which are useful for current and future management efforts. Our statistical loading results were more accurate than those from simple regression models. Our results indicate that TDS loading to the GSL in water year 2013 was 14.6millionmetrictons with uncertainty ranging from 2.8 to 46.3millionmetrictons, which varies greatly from previous regression estimates for water year 1964 of 2.7millionmetrictons. Results also indicate that locations with increased sampling frequency are correlated with decreasing confidence intervals. Because time is incorporated into the LOADEST models, discrepancies are largely expected to be a function of temporally lagged salt storage delivery to the GSL associated with terrestrial and in-stream processes. By incorporating temporally variable estimates and statistically derived uncertainty of these estimates, we have provided quantifiable variability in the annual estimates of dissolved solids loading into the GSL. Further, our results support the need for increased monitoring of dissolved solids loading into saline lakes like the GSL by demonstrating the uncertainty associated with different levels of sampling frequency.