This frothy flume is what 300,000 gallons of water per second looks like. A 60-hour surge of almost 75 billion gallons, it’s part of an effort to revitalize the ecosystem of the Colorado River and the Grand Canyon. Teams from the U.S. Geological Survey, the Grand Canyon Trust and 25 other agencies have been working together since 1995 to develop a plan that will mimic natural flooding to redistribute sediment that would normally wash downriver. Moving the sediment from the central riverbed to the riverside rebuilds the sandbars downstream that serve as natural habitats and backwater nursery grounds for endangered fish species such as the humpback chub, as well as camping grounds for recreational use.

This most recent discharge was the third of its kind. The first, in 1996, washed what little sediment there was downstream past the Grand Canyon and into Lake Mead. The second, in 2004, redistributed too little sand. Definitive results on the success of this last experiment should be available within the year and will serve as a guidepost for the next flow, which is as yet unscheduled.