Ongoing warming in the Southwest has bottomed out major reservoirs on the Colorado River and raised alarms among cities and farms that rely on the water.
But the region鈥檚 rapid warming and drying trend is also a threat to the environment in one of the world鈥檚 most recognizable wonders: the Grand Canyon. A longstanding program of artificial floods to save the canyon鈥檚 beaches from being eroded away now faces an uncertain future.
In the autumn of 2012, a flood swept through the Grand Canyon. Not one provided by nature, but by the engineers who cranked open the bypass tubes at the base of Glen Canyon Dam. It was the start of a program heralded by many as a triumph. Fall floods happened again in 2013, 2014, 2016, 2018.
鈥淎nd then,鈥� said U.S. Geological Survey hydrologist Paul Grams, 鈥渨e hit these drought conditions.鈥�
The program is in trouble. Lake Powell is three-quarters empty and just 40 feet above the level where hydropower production stops. It鈥檚 risky now to release floods, Grams said.
鈥淪o we have a condition now where it鈥檚 been four years since the last high flow and the sandbars have eroded a lot,鈥� Grams said.
Grams and a crew of scientists gathered at Lees Ferry on the Colorado River to launch their annual rafting trip. The team inflated boats and sorted through stacks of equipment piled high on the riverbank. Scientists Karen Koestner and Shannon Sartain are involved in the research.
鈥淲e are going to be mapping sandbars, and we鈥檒l have crews looking at vegetation on sandbars, and essentially we鈥檙e monitoring change,鈥� Koestner said.
鈥淔or me, this project started before I was born, so it鈥檚 kind of cool to be able to contribute to it,鈥� Sartain said.
Thirty years of data from river trips like this one show how beaches disappeared after the dam was built, then started to repair themselves with the help of artificial floods.
Now, they鈥檙e vanishing again, said fluvial geomorphologist Katie Chapman. 鈥淵ou鈥檒l be floating downstream and sometimes you鈥檒l see just active sand coming off鈥� and then sometimes you get these big, we call them 鈥榮hark bites,鈥� where this huge concave zone out of a sandbar will just collapse all at once,鈥� she said.
Chapman said the beaches are vital: they create backwaters for native fish and habitat for plants and animals. And for more than 20,000 river runners in the Grand Canyon every year, 鈥渢he sandbars themselves are the only durable, nonfragile environment that everyone can camp on; you don鈥檛 have to go bushwhacking to find a place to camp,鈥� she said.
Some scientists want to save the program by switching the timing of the floods from fall to spring, when snowmelt bolsters Lake Powell鈥檚 level. That could help balance the need for floods with the demand for hydropower. The decision of whether or not to flood the canyon is made by the U.S. Bureau of Reclamation with advice from representatives of tribal nations, water users, and environmental groups. Among them is Matt Rice of American Rivers.
鈥淚f we fail, the Grand Canyon could go dry,鈥� Rice said. If Lake Powell drops to 鈥渄ead pool,鈥� no water can pass through the dam. That鈥檚 not expected to happen , but Rice points out in a climate changed world, the drought may never end.
鈥淯ltimately I think we have one tool,鈥� Rice said. 鈥淲e have to use less water.鈥�
Rice said his goal is to make sure the pain of water shortage doesn鈥檛 fall unfairly on the environment. 鈥淚 think about the Colorado River and the Grand Canyon every morning when I wake up and every night when I go to bed. I have to be optimistic鈥�. If this place isn鈥檛 worthy of saving, then what in the world is?鈥�
The U.S. Bureau of Reclamation declined to give an interview for this story, but told KNAU in an email, the agency is in the process of determining whether to release a fall flood this year.
This story is part of ongoing coverage of the Colorado River, produced by KNAU and distributed by 萝莉少女.
