The Crested Butte News Serving the Gunnison Valley since 1999
“The ecosystem has recovered really fast”
by Seth Mensing, WCU
With a wide net, a pair of sandals, and an insatiable curiosity about life beneath the water line, Ashlynn Mixon is on the hunt for recolonizers.
In the parts of Glen Canyon that were once Lake Powell, the first-year Western Colorado University graduate student is probing the depths of streams and puddles, looking for clues about how aquatic invertebrates and other life might rebound after the water recedes in what had been the nation’s second-largest reservoir.
“It’s a really cool place,” Mixon said. “It’s unlike anything around, especially with the water levels changing, because you’ll be standing there and seeing where the water used to be. It’s a surreal experience.”
As of late June, Lake Powell is 173 feet below full pool – a height 20 feet taller than the Statue of Liberty – leaving many of the 96 side canyons that branch off the main stem of the Colorado River exposed to air and light for the first time in years, if not decades.
Last summer, Mixon, along with her advisor, Dr. Susan Washko, toured some of the exposed canyons with The Glen Canyon Institute (GCI), a Utah-based non-profit “dedicated to the restoration of Glen Canyon and a free-flowing Colorado River through Grand Canyon.”
This summer, they returned to the newly exposed borderlands between Utah and Arizona with representatives of GCI to contribute what they could to a more complete understanding of how the ecosystem has changed since the water level dropped, reconnecting the canyons to the surrounding landscape.
“Glen Canyon is well known for being a ‘lost national park’ that is re-emerging from being submerged under Lake Powell,” Dr. Washko said. “It’s a dream to be able to apply my area of work to such a special place.”
Over four days in May, she and Mixon traveled by pontoon boat between towering sandstone cliffs to the eastern reaches of Lake Powell, where they slept on exposed beaches at the mouth of side canyons, before hiking up and in to where life is starting to reestablish itself. “You only have to hike a few miles to get into areas with a lot of cottonwoods,” Mixon said. “So the ecosystem has recovered really fast.”
Because Glen Canyon is a National Recreation Area and therefore a low priority for scientific study, until Dr. Washko and Mixon arrived, they couldn’t find any evidence that an entomologist had ever studied the aquatic invertebrates there. The only record of the canyon’s bug life they could find was in an archaeology journal published before the dam was built, and the reservoir started to fill in 1966.
Since then, the Colorado River, one of the most sediment-laden rivers in the world relative to its water flow, has deposited a layer of silt and sand up to 150 feet thick where the fast-running river water meets the reservoir.
And as the reservoir’s water recedes, plants have started to take root, inviting birds and bugs to recolonize areas that had been occupied only a few years before by introduced fish and invasive quagga mussels.
Aquatic macroinvertebrates are important indicators of water quality and ecosystem health. By comparing macroinvertebrate communities exposed for different lengths of time, Mixon hopes to understand how quickly ecological succession is occurring in the recovering canyon system.
“Being the first to work on this is exciting because we can really help build a foundation of knowledge that natural resource managers can reference to develop further research informing decision-making around habitats in reservoirs with decreasing water levels,” Dr. Washko said. “In the case of Lake Powell, water levels have been dropping for so many years that restoration is naturally occurring as the habitat is unsubmerged.”
Over the last year, since her first visit to Glen Canyon, Mixon has been conducting a geospatial analysis of the area to determine when different areas of the canyon were covered by water and for how long before being exposed again.
During their survey, Dr. Washko and Mixon found soldier fly and black fly larvae, aquatic snails, and several kinds of beetles. Mixon’s hypothesis is that communities above the high watermark will be more diverse and richer than those once submerged. An analysis of their findings over the next year will determine if that’s true.
“I’m interested in seeing the difference between above and below the high-water mark,” Mixon said. “I think it probably will never recover exactly to what it once was. But those side canyons are so prone to flash floods, kind of giving them a fresh start. So, with things like that happening, the ecosystem has recovered really fast.”
For researchers who have the opportunity to explore an area that has recently reemerged, Glen Canyon represents not only the return of a lost landscape but also the opening of a new scientific frontier.
“So far, our biggest lesson learned has been not to underestimate the canyons,” Dr. Washko said. “Walking through them, knowing they used to be underwater, there’s still so much life and beauty there. I hope that this theme is as apparent in the data as it was to our eyes as we hiked.”
For more information about Western’s Master of Science in Ecology program, visit western.edu.
