Desert ecosystems are inherently fragile environments. Unfortunately, with the invention of air-conditioning, society has increasingly diverted scarce water to development cities such as Phoenix, Arizona and Las Vegas, Neveda in the desert. Scarce water has also been used to generate electricity through hydroelectric projects and to water agriculture fields planted in the desert. All of this has strained the capacity the Colorado and other rivers to deliver water to downstream sources, with the result that the lower parts of such rivers have become increasingly salty and unable to support life. Meanwhile, droughts and increasingly population put a strain on water supplies used to provide water and electricity to desert cities.