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Hydrologic Extremes

In the Great Salt Lake Basin, climate varies greatly over short and long time scales, with intermittent large events. This large temporal variability in climatic properties is not well documented by typical climatological measures such as 30-year means. Probabilities of future climatic events are conditional upon the present and recent past. The occurrence of low frequency events of large magnitude may carry strong implications for hydrologic processes. It is hypothesized that these events create effects that far outweigh their relatively uncommon nature. Significant events and their temporal distribution need to be examined using other techniques than the usual central tendency statistics. The need to determine how this behavior governs the hydrology of the region leads to the following questions:

What is the outlook of episodic flooding events and inundation due to rises in the lake level?

What are possible realizations and frequencies of drought, and the effects on water resources?

How do these events alter feedbacks between the surface hydrology and atmospheric processes?

From 1963 through 1986, the Great Salt Lake rose nearly 20 feet, more than doubled its surface area, and increased its volume nearly three-fold. Almost 12 feet of the rise occurred during the period between 1982 and 1986, attributed to record amounts of precipitation in the northern Utah drainage areas that feed the Great Salt Lake. Inflow to the lake in 1986 was more than double the normal average. On June 5, 1986, the level of the south arm of the Great Salt Lake reached a new record historic high elevation of 4211.85 feet above sea level. The lake reached the same level again in 1987. At this modern record level, the lake covered approximately 2,400 square miles and contained more than 30 million acre-feet of water. For perspective, its expanse was only about 487 square miles less than the states of Delaware and Rhode Island combined, and the lake contained an acre-foot of water for every resident of Utah, Idaho, Wyoming, Montana, Colorado, North Dakota, South Dakota, Nebraska, Iowa, Kansas, Oklahoma, New Mexico, Arizona, Nevada, Oregon and Washington.
Source:  Utah Division of Water Resources

Flooding of the Great Salt Lake Near Brigham City during 1983
Source:  Utah Division of Water Resources

Record amounts of precipitation in the mid 1980s caused the Great Salt Lake to rise to historic levels, causing flood damages to public and private land, industries, major transportation routes, public facilities, and wildlife habitat estimated at more than $240 million. Potential cost of damages was estimated at $1 billion, figuring affected company payrolls, tax payments, capital expenditures and purchases.

Flooding in downtown Salt Lake City during 1983
Source:  USGS

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