Great Salt Lake approaches 167 year record low


True color satellite image of the Great Salt Lake on August 18, 2014. (NASA)

Dry winters are taking their toll on the Great Salt Lake, which is just a couple feet away from reaching its record low level, set over 50 years ago.

Utah’s Great Salt Lake, which is the largest salt water lake in the western hemisphere, has been on a gradual decline over the past few years, and is now about two and a half feet away from its record low level of 4,191.35 feet. In 2014 alone, the lake has been losing around half a foot per month since May.

While the mountainous area that feeds the lake saw above average snowfall in the 2013-2014 winter, it wasn’t able to overcome the impact of previous years’ dismal snow packs.

According to the Utah Geological Survey, the Great Salt Lake fluctuates through the year. In the spring, melting snow pack lifts the level to its highest point from May through July. The lake is at its lowest from October to November, which means there are still a few months to go before it bottoms out for the year.

(USGS)
Daily elevation of the Great Salt Lake since August 2013. (USGS)

The Utah Geological Survey says:

In historical time (1847 to present), fluctuations of the lake level have varied over a range of 20 feet from a low of 4,191.35 feet in 1963 to a high of 4,211.85 feet in 1986-1987. The historical average elevation of the lake is about 4,200 feet.

Elevation of the south arm of the Great Salt Lake since the mid 19th century. The lake's record low level of 4,191.35 feet was recorded in 1963. (Utah Geological Survey)
Elevation of the south arm of the Great Salt Lake since the mid 19th century. The lake’s record low level of 4,191.35 feet was recorded in 1963. (Utah Geological Survey)

Because the Great Salt Lake is so shallow, small fluctuations in the lake’s level can cause extreme shifts in the location of the shoreline. The average depth of the lake is only 16 feet in an average year, which is spread out across 1,700 square miles.

Compare that to 3,300 square miles, when the lake was at its record high depth of 33 feet. At its record low in 1963, the lake only covered 950 square miles, according to the USGS, which means a loss of 8.5 feet in elevation resulted in a 44 percent decrease in surface area.

(USGS)
Small changes in elevation lead to large shifts in the shoreline. The average area of the Great Salt Lake is in blue. The historic high level is outlined in red, and the historic low level is outlined in black. (USGS)

The Bear, Weber, and Jordan rivers supply the majority of the lake’s water, and since there are no outlets, evaporation is accountable for any decrease in water. Interestingly, the high salinity of the lake also acts to decrease the rate of evaporation. As the amount of water in the lake decreases, the salinity increases (the minerals in the lake do not evaporate into the air), which decreases the rate of evaporation.

As the water evaporates from the lake, the shoreline is receding, which exposes the floor of the lake and has the potential to permanently park boats through the winter, until the next high water season in the spring. This year’s exceptionally low lake levels are forcing Salt Lake boat owners to find a new storage situation. By early August, 70 boats had been removed by crane from the Great Salt Lake Park Marine, Reuters reports.

But the news isn’t all bad. Oddities are surfacing as the lake shrinks. Boats that have sunk over the centuries have started to appear, visible to the eye from the surface as the lake water clears.

The Salt Lake Tribune reports that among the ruins is the possible wreckage of a cattle boat that was ordered to be built by Mormon prophet Brigham Young. And a ship that was used to construct and maintain the Lucin Cutoff trestle that runs across the northern Great Salt Lake. That boat, which hasn’t been seen afloat since it sank in 1936, is now visible from an observation deck at the Great Salt Lake State Marina.

Angela Fritz is an atmospheric scientist and The Post's deputy weather editor.
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