John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
The nation's second-largest manmade reservoir has shrunk down to a virtual muddy pond.
Optimists would say this reservoir is half full. They'd be wrong: Lake Powell, the nation's second-largest manmade reservoir, was at only 42 percent capacity as of Tuesday.
Powell provides water and electricity to a bunch of Western states, but it's getting dangerously close to becoming a useless puddle after more than a decade of drought. The reservoir's diminished state is clear in these images snapped by the Landsat 8 satellite. Above, the lake's northern section in Utah is slightly moistened by a muddy Colorado River. Bleached rocks the color of ivory show where water stands when the reservoir is full.
Compare this part of Powell to what existed in March 2013, as seen on Google Earth. It's like night and day:
And here's the reservoir nearer to Arizona's Glen Canyon Dam, as shown on a map the National Park Service provides to visitors. It looks like the water levels were once high enough there was a way to cross from Halls Creek to Bullfrog Bay without going into the main channel:
Good luck to anybody who tries that today. You'd need the Terminator's stamina to portage an expanse of dusty desert:
NASA lays out how the reservoir has fallen onto hard times:
It is normal for water levels to fluctuate in the reservoir depending on how much water flows in from snow and rain and how much flows out to meet needs. However, it has been dry in all but three of the past 14 years. At the beginning of 2000, Lake Powell was at 94 percent of capacity. By October 2013 (the beginning of the 2014 water year), water levels had dropped to a low of 50 percent capacity, according to the Bureau of Reclamation, the agency that manages the reservoir.... With slightly above average snowpack in the basin that feeds the lake, water levels are expected to rebound to about 51 percent of capacity by October 2014, the end of the water year.
If the reservoir's situation gets much worse in the coming years, many states could be looking at water restrictions and a "shutdown of hydropower generation," according to the environmental group Circle of Blue. That threat has water managers wondering if they should open dams upriver to restock Powell's supply, or ask or pay farmers to stop growing crops. As one Colorado River administrator told the group: "We want to plan for extreme hydrology the likes of which we have never seen."
Images courtesy of NASA