Earth Notes: The Returning Rapids Of Lower Cataract Canyon
Rapids are returning to lower Cataract Canyon in southern Utah after decades underwater in the far-upper reaches of Lake Powell. The damming of the Colorado River in Glen Canyon in the 1960’s submerged the river’s channel and native vegetation. But climate change, extended drought and extreme heat have caused Lake Powell’s water level to drop to new lows, revealing the once-submerged rapids.
Two river runners from Moab - Mike DeHoff and Peter Lefebvre - have launched an effort to monitor the emerging rapids. The Returning Rapids Project is designed to document the changing river through lower Cataract Canyon as Lake Powell’s water level drops. To predict where rapids will appear, they use a historic scroll map marking old rapid locations. Repeat photography and time-lapse videos document the river becoming turbulent as boulders break the surface.
This rapid rebirth depends on the erosion of the Lake Powell Formation, the thick layer of mud deposited by the reservoir as it recedes. This sediment filled in when the river was dammed. Now, the receding water scours mud to reveal boulder fields, the backbone of rapids.
The riparian ecosystem is also changing. Otters and beavers have returned downstream, and native trees are sprouting along the banks. Fast-growing willows cover new sandbars with shade, providing comfortable spots for all kinds of animals, including humans documenting the emerging rapids of lower Cataract Canyon.
This Earth Note was written by Michaela Sallue, as part of a student collaboration with the Sustainable Communities Program at Northern Arizona University.