THE GREAT SALT LAKE BASIN HYDROSYSTEM: A PALEOLIMNOLOGICAL PERSPECTIVE

Owing to growing populations, demands for freshwater and energy are increasing and water crises are predicted in many parts of the western United States. The Great Salt Lake Basin is an excellent example of a region where rapidly expanding populations are expected to stress water resources. This basin is typical of many hydrologic basins in the western United States in that snow from mountains is the main water supply for the relatively arid valleys. It is also typical of western basins in that anthropogenic activities are decreasing water quality.

In order to accurately model the Great Salt Lake Basin hydrologic system and make predictions about future water resources in this region, it is critical to have an understanding of the baseline conditions, natural variability and trends of both the quality and quantity of water resources. In order to determine these factors for any hydrologic system, long-term (centuries to millennium) data are required. Unfortunately, actual measurements of key components of hydrologic systems (i.e., precipitation and evaporation) in the western United States rarely, if ever, extend for more than 50-100 years. Water quality data is even more limited. Therefore, proxies of these variables are required. Geochemical and biological signals preserved in lake and reservoir sediments provide information about water quality and quantity over long time scales. For example, diatoms, unicellular algae characterized by a siliceous cell wall, are preserved in lake sediments and variations in species composition over time can be used to provide long-term, quantitative records of effective moisture (precipitation – evaporation). These records can be used to determine variations in the magnitude, frequency and duration of drought. Geochemical data can reveal the long-distance transport of pollutants to lakes, and biological remains (e.g., diatoms) can indicate changes in water quality over time. Several ongoing studies from the Great Salt Lake Basin, including research at Bear Lake, the Uinta Mountains and East Canyon Reservoir, will be used to illustrate the importance of a long-term perspective for understanding and modeling hydrosystems such as the Great Salt Lake Basin.