Water in the West Desert Basin
By Winston Seiler (WEST Fellow 2005-7)
By area, the West Desert Basin covers nearly 20 percent of Utah. This expanse holds both tall, alpine peaks and lowland, high-desert scrubland valleys. Situated in the northeastern portion of the basin is Great Salt Lake, the western United State’s largest inland water body. In order to study the water cycle affecting Great Salt Lake and the Wasatch Front, it is important to understand the hydrology of the larger West Desert Basin.
Elevation within the West Desert ranges from 4,200 feet in the valleys to over 12,000 feet in the mountains and precipitation varies from
as little as 5 inches of precipitation on valley floors to as much as
35 inches of precipitation at higher elevations each year. Water in
the West Desert is not abundant, and its availability
from year to year can vary dramatically. Within the desert, surface
flowing streams are rare and generally soak into valley floors upon
exiting mountain canyons. Of the water that enters the ground,
approximately 54,000 acre-feet migrate into Great Salt Lake,
supplying about two percent of the lake’s annual inflow.
Only two percent of the state’s
population, approximately 40,000 people, reside within the West Desert expanse. Of these residents, 90
percent can be found in the Tooele and Rush Valleys. The Tooele and
Rush Valleys occupy over 769,000 acres, of which the vast majority is
in a natural state. 33,000 acres are cultivated.
The valleys receive
an average of 14.7 inches of rain each year, with accumulations in
mountainous regions far exceeding that on the valley floors. This equates to about 941,500
acre-feet of water input into the Tooele and Rush Valleys each year.
Of this initial input, 809,000 acre-feet (86%) are lost to
evapotranspiration from native plants and introduced agriculture. Most
creeks quickly dry upon exiting mountain canyons, with water
infiltrating into the sedimentary valley fill. This water percolates
downward through sediments to accumulate in the Tooele/Rush aquifer.
From this groundwater supply, 85,400 acre-feet (9%) are removed for
agricultural and crop irrigation—in fact agriculture is the largest
single human consumer of water in the entire West Desert Basin. An
additional 35,350 acre-feet (4%) are pumped for industrial and
municipal use. This leaves a net gain of 11,750 acre-feet of water to
recharge the groundwater supply annually—about one percent of the
initial volume of water received as precipitation. Of this one
percent, only a third of it, 3,300 acre-feet are estimated to reach the
Great Salt Lake.
  Scientists study the water cycle of the West Desert Basin by closely monitoring how much water enters the basin by precipitation, and by accounting for how much water is removed from the area by evapotranspiration by plants and though human use. To determine how much water enters the desert, meteorologists monitor a number of weather stations that can record precipitation amounts, temperature, and humidity. Biologist studying the types of plants and where they are found in the desert are able to calculate the amount of water consumed by the plants and transpired into the atmosphere during photosynthesis. Geologists are able to study the rocks and soil found in the mountains and valleys in order to understand how water soaks into the ground. By monitoring gauges on streams, hydrologists can determine the amount of flowing water in surface streams. Geographers can examine data recorded at pumping stations to determine how much water is removed from the ground by people to water their crops, fill pools, and drink. Finally, computer scientists can take all this information to create models to understand how water moves through the West Desert Basin. In total, understanding the area’s water budget requires different scientists working together to understand the larger world around them. -- Adapted from Utah Division of Water Resources, 2001
Click here for Resources for Educators. Click here for News and Information about water in the West Desert Basin. References:Utah Division of Water Resources, 2001, Utah State Water Plan, West Desert Basin: Utah Department of Natural Resources, Salt Lake City, 216 p. http://www.water.utah.gov/ http://www.water.utah.gov/planning/swp/ex_swp.htm
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