Scientists continue work to navigate intricate web of water sources feeding Hanging Lake
Tracing the source waters of Glenwood Canyon’s iconic Hanging Lake is a little like a game of whack-a-mole.
Last weekend, scientists from the Ozark Underground Laboratories, based in the little town of Protem, Missouri, just a few miles north of the Arkansas state line, spent five days high in the Flat Tops introducing special dye into four headwater sources above the north rim of the canyon.
Some of that water stays on the surface, including in the east fork of Deadhorse Creek — a known source of the water that pours through Spouting Rock and over Bridal Veil Falls into Hanging Lake, then spills over the cliffs below into the lower reaches of West Deadhorse Creek.
What’s not fully known is how much of that water leaves the stream 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 extensive mud and debris flows into the canyon when it saturated the 2020 Grizzly Creek Fire burn scar.
The group is working with the U.S. Forest Service, National Forest Foundation and other organizations, using part of the Glenwood Canyon restoration funds that were raised, to try to trace Hanging Lake’s source waters.
“The goal of this study is to be able to inform managers with the Forest Service in particular where the water is coming from that ends up in Hanging Lake,” Woods said. “That 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 from the fire and the ensuing flood damage, though the trail leading to the lake was covered with several feet of mud, rocks and tree branches in spots.
A primitive trail reopened to hikers in late June under the Forest Service’s fee-based permit system to regulate public access into the area.
Nontoxic fluorescent tracer dye was placed in East Deadhorse Creek early last October, and researchers expected to see traces show up in the carbon samplers they had located in and around Hanging Lake because of that 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 went into the ground before it ever got to Hanging Lake,” he said.
Scientists are aware of the many “losing stretches” of surface streams that come into the canyon, where water goes underground and sometimes emerges a drainage or two over.
In this instance, the dye placed into East Deadhorse wound up in French Creek to the east of Hanging Lake.
Yet, “we put dye in the headwaters of French Creek, and we haven’t found that anywhere,” Woods said. “We’re not sampling east of French Creek, so we don’t know where that 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 the White River National Forest.
“This year, the goal is to get a better handle on the western and northern boundaries of the recharge area, and to do some introductions in areas that were highly impacted by the wildfire,” Woods said. “That will help us better narrow down where the water is coming from, and since we don’t have to wait for snow melt to get the results, maybe get a better idea of travel times.”
Another hike up to Hanging Lake this week involved the placement of carbon tracer cartridges at strategic points along the creek, at the lake and at Spouting Rock.
The samplers are tied onto rocks, downed trees or exposed roots and wouldn’t even be noticed by a hiker passing by, Osorno said.
The dye itself is nontoxic and also wouldn’t be very visible by the naked eye, he explained.
Ozark Laboratories’ analytical equipment can measure dye in the 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 do studies on some of these prominent natural landmarks,” Osorno said. “A lot of the other stuff we do is what pays the bills … remedial projects where they need to know where the water is going and designing systems for cleanup of mine sites and stuff like that.
“That then affords us to do these kinds of conservation work projects that I think the staff ultimately feels is high value work,” said Osorno, who has a master’s degree in geology and is finishing his doctoral work through 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 off or altered by a major debris flow or another fire event.
“If you go up on the plateau and you look at, say, Grizzly Creek or Deep Creek, there are very well-defined stream channels,” Woods said. “That’s characteristic of a basin that carries the majority of surface flow.
“But the creek channels in the east and west parts of Deadhorse are not very well defined,” he said. “It’s a lot of grassy basins, and there’s really no good channel until you get well into the canyon.”
That’s indicative of the karst landscape where water is going underground rather than flowing on the surface.
Hanging Lake was formed by travertine (calcium carbonate) dams that built up through geologic time from the constant flow of mineral-rich spring waters. It’s a unique chemical process that’s common in caves, but it is quite rare for it to form on the surface, Woods said.
There are two main concerns with Hanging Lake, he said.
One is the potential physical threat to the lake from a debris flow.
The other has to do with water chemistry, and maintaining the water chemistry that promotes the travertine deposition, he explained.
“We’re not looking at water chemistry with this phase of the study, but before anybody can look at water chemistry, you have to know what water to look at and where the water is coming from. So that’s our job here,” Woods said.
The earlier experiment did detect water coming into Hanging Lake from West Deadhorse Creek. But it had to have traveled underground to get there.
West Deadhorse runs dry on the surface this late in the season, except for below Hanging Lake. And there’s not a direct surface connection to the lake from that side.
“We know we’re getting water from the west fork, so that has to be groundwater flow,” he said. “If we get anything from our samples today, that will indicate a really fast travel time, but we’re not sure what to expect.”
The water coming through Spouting Rock, a quartzite formation, is also groundwater.
By comparing that flow that’s coming into the lake to the known surface flow, researchers can also begin to estimate the proportion of groundwater versus surface water that’s feeding the lake, he said.
Woods said the Forest Service staff assistance has been crucial in running the samples locally. He also credited the Colorado Cave Survey for helping point out areas on the plateau where the dye introductions would be most effective.
“Our practice has been doing projects like this since the 1970s,” he said. “We’ve done work in every state in the U.S. and on all of the continents, except Antarctica.”
Much of that work involves delineating recharge areas for sensitive karst features or for rare, threatened and endangered species.
“We also do a lot of remedial work and monitoring of wastewater plants, landfills, things like that,” he said. “But we really enjoy doing conservation-related projects like this, and the protection of natural resources.”
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