GLENWOOD CANYON – Standing on the boardwalk at the edge of Hanging Lake, seeing it all for the first time, Trevor Osorno noticed two things in particular: How striking the turquoise lake appeared and how much water was cascading off the roots and rocks above the lake down into the mineral-rich pool.
“It’s pretty damn cool,” said Osorno, a senior hydrogeologist at Ozark Underground Laboratories. “More flow than we saw up canyon, that’s for sure.”
Osorno and his Ozark colleague, Dave Woods, spent the previous several days camping out at a U.S. Forest Service cabin on the Flat Tops above Glenwood Canyon. The pair were hired by the Forest Service to conduct research aimed at determining the source of the water flowing into Hanging Lake, one of Colorado’s most prized outdoor spots.
After the Grizzly Creek Fire ripped through the canyon two years ago, burning more than 30,000 acres, yet somehow sparing Hanging Lake, the Forest Service realized it did not have a good grasp of the origin of the water that flows into the lake, a National Natural Landmark.
“The fire highlighted that we don’t really know or have a good understanding of the hydrology, where the water comes from that feeds Hanging Lake,” David Boyd, a spokesman for the Forest Service, said.
Enter Woods and Osorno from Ozark, a Missouri-based company that specializes in tracing source water. The Ozark mappers conduct their work by dropping dye into different drainages above the lake and sampling the water below to track where it’s coming from.
“Our goal is to delineate the recharge area of Hanging Lake, and that involves figuring out where the water is coming from,” Woods said. “Nobody knows right now – and we’re starting to get an idea.”
The Forest Service’s Boyd said this research, which is being funded by the National Forest Foundation, would help the agency make strategic decisions about anything that might affect the lake in the future – trail rerouting, logging projects or anything else related to forest health – as well as help with understanding where any potential impacts might be from a future forest fire.
Last September, in their first field visit, Ozark researchers, including Woods, placed dye into three headwaters above the lake – the east and west forks of Deadhorse Creek and French Creek. The first dye detections showed up in May.
Although the east fork of Deadhorse Creek drains directly into Hanging Lake, the researchers did not find that dye in their samples from the lake; that dye did, however, end up in French Creek, suggesting a groundwater connection.
Dye from the west fork of Deadhorse did show up in the lake, even though there is no surface water connection between the two, also suggesting an underground connection. The west fork dye was placed 5.5 miles away and 2,500 feet above Hanging Lake.
The researchers did not find traces of the dye they placed in French Creek, meaning it could have traveled to another basin the researchers are not monitoring.
This month, Woods returned for a second round of field work. He brought along Osorno, who was seeing the canyon and the lake for the first time. The Ozark team’s goal for this trip was to continue narrowing down the lake’s recharge area, focusing on the western and northern boundaries.
This time, the team placed dye into flowing water in four new spots on the plateau above the lake, three in major surface drainages and one in a cave. Last year, there was very little running water during their trip in September, and so the team had to wait for the snowmelt to get their detections.
“This year we did find flowing water up there,” Woods said. “Not a lot, but we found some, so we were able to get dye in the flowing water, which was good.”
The Forest Service is assisting Ozark by collecting water samples from Hanging Lake as well as from the water flowing below the lake. The researchers collect dye samples by using a pouch containing an activated carbon substance made from charred coconut that can detect dye flowing by, even in extremely small amounts. Wood said the dye is commonly used for this purpose globally, not toxic and not harmful to wildlife.
“Most of the time, when we get our detections, the average person wouldn’t even know there’s dye in the water,” Woods said. “In fact, we wouldn’t even know there’s dye in the water.”
“Two or three magnitudes lower than a visual detection limit is what we can see,” Osorno said of the Ozark sampling method.
Depending on how quickly the dye shows up in samples collected by the Forest Service, this round of Ozark field work might also give the researchers a sense of how long it takes any source water to move into the lake. Woods said they could have new data in the next week or two.
Woods said that although Ozark has conducted numerous water-tracing projects, this one is notable because of the setting.
“This is a pretty spectacular opportunity,” he said. “We do work all over, but this is a great one because of where it is and the lake.”
That beauty, however, also makes for hard work.
“We’ve had to hike around a lot into some pretty crazy places to get dye into the ground,” Woods said. “It’s been difficult, but it’s been really rewarding, and I think we’re getting some good results.”
