Preface • Introduction • Study Objectives • Community Participation • Regional, Physical and Ecological Setting
Regional, Physical and Ecological Setting
The GSL is located at the lowest point of a 35,000 km2 drainage basin (between 40º and 41º N, 113º and 112º W). This places the lake on the eastern edge of the Great Basin embracing the west escarpment of the Wasatch Range. One of the four largest terminal lakes in the world, the GSL varies in size as it expands and contracts in cadence to changing moisture patterns.
The GSL sits in a high elevation, cold desert region modified by arid mountain-framed basins. Temperatures range from 38º C in summer to -18º C in winter. Great Salt Lake’s west side habitats are xeric, receiving less than 25 cm of annual moisture. In contrast, the east side receives 38 cm. The east margins of the lake fall under the influence of the “Lake Effect:” as warmer air lifts off the GSL, it condenses at higher elevations of the Wasatch Mountains.
The GSL ecosystem is an extensive complex of salt water, wetlands, uplands and drainage systems occupying roughly 7,800 km2; it becomes more impressive as one considers its regional and hemispheric setting. Except for the moister mountain ranges and high elevation valleys, the GSL sits in an expansive dry sweep of land in Western North America. This region extends from the Canadian Prairies to the Tropic of Cancer and receives less than 50 cm of precipitation annually. Because of the surrounding desert, the GSL acts as an oasis for waterbirds as they explore breeding habitats and establish migratory pathways within and across this arid expanse. For many species the lake is their migratory “halfway point” between northern breeding grounds and southern wintering locations. In this case, the lake is an important refueling site with seasonally abundant invertebrate resources.
GSL habitats are varied and in some cases unique among salt lakes of Western North America. The following is a description of GSL habitat types (Aldrich and Paul 2002).
The terminal nature of the lake with its various saline systems and associated halophiles contribute greatly to the uniqueness of the natural wonders that happen there. The Great Salt Lake is a playa lake with an extremely low-gradient bottom. When the surface elevation is 4202 feet above sea level, the average depth of the lake is four meters. With the seasonal recharge of water from rivers and other drainages and subsequent evaporation, the effect of this shallow flat bottom is most apparent in the highly transitory shoreline. The result is ephemeral pools, expansive mud flats and sand bars that warm quickly in spring and easily reach temperatures around 29º C in summer. Some parts of the lake shoreline migrate more than 800 m from spring to fall depending on the levels of water recharge and evaporation that year. These water depth and shoreline fluctuations are fundamental ingredients in the creation of highly productive habitats for wading waterbirds.