See inside Glen Canyon Dam as Lake Powell levels drop

This article was originally featured on High Country News.

Glen Canyon Dam was built primarily to store excess Colorado River water during wet years, so it could be released during dry spells and used to generate power. Now, with aridification depriving the river of those excess flows, both functions are imperiled. In April, Lake Powell fell perilously close to the point at which dam operators would have to stop sending water through the turbines, depriving the grid of enough electricity to power about a quarter of a million homes annually. It would also drain between $100 million and $200 million annually from dam electricity sales, some of which helps fund endangered species recovery, salinity control and water studies on the Colorado River. Officials have released extra water from upstream dams and are currently letting less of it flow through Glen Canyon Dam, raising water levels just enough to keep the turbines spinning. —Jonathan Thompson