Tracing the water sources of Glenwood Canyon’s iconic Hanging Lake is a bit like a game of molesting.
Last weekend, scientists from Ozark Underground Laboratoriesbased in the small town of Protem, Missouri, a few miles north of the Arkansas state line, spent five days in the Flat Tops introducing a special dye to four headwater springs above the north edge of the canyon.
Some of this water remains on the surface, including in the East Fork of Deadhorse Creek – a known source of the water which spills through Spouting Rock and over Bridal Veil Falls into Hanging Lake, then spills over the cliffs below in the lower reaches of West Deadhorse Creek.
What is not fully known is how much of this water leaves the creek channels descending into Glenwood Canyon and flows underground into the massive karst (cave) system below the surface.
There’s also the question of where it goes from there and how long it takes to come back to the surface.
Last fall, Dave Woods and his team of groundwater scientists from Ozark Laboratories came to Colorado after record rainfall triggered major flows of mud and debris in the canyon when they saturated the scar of Grizzly Creek Fire burn in 2020.
The group is working with the US Forest Service, the National Forest Foundation and other organizations, using a portion of the Glenwood Canyon restoration funds that have been raised, to try to trace Hanging Lake’s water sources.
“The purpose of this study is to be able to tell Forest Service managers specifically where the water that ends up in Hanging Lake is coming from,” Woods said. “It will give them an idea of the impacts of wildfires and different management strategies to protect resources like Hanging Lake.”
The unique travertine lake formation itself was spared fire and flood damage, although the trail to the lake was covered in several feet of mud, rocks and tree limbs in places .
A primitive path reopened to hikers end of June under the Forest Service fee-based permit system to regulate public access to the area.
A non-toxic fluorescent tracer dye was placed at East Deadhorse Creek early last October, and the researchers expected to see traces appear in the carbon samplers they had located in and around Hanging Lake due to this direct surface flow.
“We didn’t get that particular dye in Hanging Lake,” Woods said of the return trip this spring to check the samplers.
“The dye got into the ground before it even reached Hanging Lake,” he said.
Scientists are aware of the many “lost reaches” of surface streams that enter the canyon, where water passes underground and sometimes emerges a drainage or two.
In this case, the dye placed in East Deadhorse ended up in French Creek east of Hanging Lake.
Still, “we put dye in the upper reaches of French Creek, and we couldn’t find it anywhere,” Woods said. “We’re not sampling east of French Creek, so we don’t know where this dye went.”
On Tuesday, Woods and his senior hydrogeologist Trevor Osorno were back on the Hanging Lake Trail to do it all over again. They were joined by Forest Service interns Lorraine Negrón and Neil Hooker, and Colleen Pennington, Glenwood Canyon Recreation Manager for the Eagle-Holy Cross Ranger District of White River National Forest.
“This year, the goal is to get a better handle on the western and northern edges of the recharge area and do some introductions to areas heavily affected by wildfires,” Woods said. “It will help us better determine where the water is coming from, and since we don’t have to wait for the snow to melt to get the results, we may have a better idea of travel times.”
Another hike to Hanging Lake this week involved placing carbon tracer canisters at strategic points along the creek, at the lake and at Spouting Rock.
The samplers are tethered to rocks, downed trees or exposed roots and would not even be noticed by a passing hiker, Osorno said.
The dye itself is non-toxic and also wouldn’t be very visible to the naked eye, he explained.
Ozark Laboratories’ analytical equipment can measure the dye in parts per trillion, so it doesn’t have to be seen in the water for it to be detected in the field lab.
“It’s very rewarding to study some of these important natural sites,” Osorno said. “A lot of the other things we do are what pays the bills…repair projects where they have to figure out where the water is going and design systems for mine site cleanup and things like that.
“It then allows us to do these kinds of conservation work projects that I think the staff ultimately see as high-value work,” said Osorno, who has a master’s degree in geology and is completing his doctorate at the University of Kansas, specializing in how contaminants are transported through underground aquifers.
A potential threat to Hanging Lake would be if the various underground water channels that feed the lake were to be cut or altered by a major debris flow or other fire.
“If you go up on the set and look at, say, Grizzly Creek or Deep Creek, there are very well defined stream channels,” Woods said. “It is the characteristic of a basin that carries the majority of surface runoff.
“But the creek channels in the eastern and western parts of Deadhorse are not very well defined,” he said. “There are lots of grassy pools and there really isn’t a good channel until you’re well in the canyon.”
This is indicative of the karst landscape where water goes underground rather than flowing on the surface.
Hanging Lake was formed by dams of travertine (calcium carbonate) that built up over geologic time from the constant flow of mineral-rich spring waters. It’s a unique chemical process that’s common in caves, but it’s fairly rare for it to form on the surface, Woods said.
There are two main concerns about Hanging Lake, he said.
One is the potential physical threat to the lake from a debris flow.
The other is about water chemistry and maintaining water chemistry that promotes the deposition of travertine, he explained.
“We are not looking at water chemistry in this phase of the study, but before anyone can look at water chemistry, you need to know what water to look at and where it comes from. So that’s our job here,” Woods said.
The previous experiment detected water entering Hanging Lake from West Deadhorse Creek. But he had to travel underground to get there.
West Deadhorse dries out on the surface this late in the season, except below Hanging Lake. And there is no direct surface connection with the lake on this side.
“We know we’re getting water from the West Fork, so it must be underground flow,” he said. “If we get anything from our samples today, it will indicate a very fast travel time, but we’re not sure what to expect.”
Water from Spouting Rock, a quartzite formation, is also groundwater.
By comparing this flow entering the lake to the known surface flow, researchers can also begin to estimate the ratio of groundwater to surface water feeding into the lake, he said.
Woods said assistance from Forest Service personnel was crucial in running the samples locally. He also credited the Colorado Cave Survey for helping identify areas of the shelf where dye introductions would be most effective.
“Our firm has been doing projects like this since the 1970s,” he said. “We have worked in every state in the United States and on every continent except Antarctica.”
Much of this work involves delineating recharge areas for sensitive karst features or for rare, threatened and endangered species.
“We also do a lot of repair work and monitoring sewage treatment plants, landfills, things like that,” he said. “But we really like doing projects related to conservation like this and the protection of natural resources.”