Years of drought and over-irrigation have caused Utah's Great Salt Lake to shrink at an alarming rate, recent satellite photos show.
After the Great Lakes, Utah's Great Salt Lake is the largest body of water (by area) in the United States. Back in the middle of the 19th century, when pioneers first arrived in the area, the lake spread across roughly 1,600 square miles (4,100 square kilometers). Now, the lake covers an area of only about 1,050 square miles (2,700 square km), new satellite photos from NASA reveal. In October, the Great Salt Lake reached its lowest level in recorded history, with the water’s surface elevation at only 4,191 feet (1,277 meters).
These dramatic declines in water levels come from years of human activity — namely, diverting river water, which would normally fill the lake, for agriculture and industry, according to NASA. The agency estimates that about 40 percent of the river's water is diverted from the lake. These activities, along with the ongoing drought in the West, have drained the historic lake. [Gallery: Rainbow of Life in Great Salt Lake]
The NASA images show changes in the Farmington Bay basin of Great Salt Lake, an area that is home to many diverse wildlife, including migratory birds. Decreasing water levels in the Bay not only affect the ecology of the area, but could divert the bird populations who migrate to the basin for food.
"Farmington Bay has been nearly desiccated as the result of the combined effects of drought and water withdrawals from the rivers feeding the lake," Wayne Wurtsbaugh, a watershed sciences researcher at Utah State University, said in a statement. "Farmington Bay is an immensely important feeding area for migratory shorebirds and waterfowl. Even at the low level we have now, it is still important, but the greatly reduced size has diminished its value."
The NASA satellite images show changes in the Farmington Bay basin from 2011 to 2016. Scientists estimate that more than three-quarters of the lake bed is now exposed in the bay, significantly diminishing the food available for wildlife.
In February, Wurtsbaugh and his colleagues released a white paper on how water development has impacted the Great Salt Lake. Their study found that river flow into the basin has been reduced by 39 percent since the middle of the 19th century. Reversing this trend would involve more conservation efforts, especially for agricultural irrigation, which accounts for approximately 63 percent of water usage in Utah, Wurtsbaugh said.
Even with conservation efforts and more ecologically conscious development, the lake could continue to diminish due to climate change, the researchers said.
"A wild card for the fate of the lake is what global climate change may do to the basin,” Wurtsbaugh said. "Warmer air temperatures are projected to lower runoff, but our data shown in the white paper suggests there haven't been climate change effects on the runoff yet."
Editor's Note: An earlier version of this story stated the lake’s lowest level was 4,191 feet deep. The story has been updated to reflect the correct measurement was 4,191 feet of elevation above sea level.
Original article on Live Science.