County, State Agencies Ponder Flood Potential
High water concerns and an increasing realization of the tremendous amount of tree debris which will be washed downstream in this and future runoffs prompted Hinsdale County Commissioners to convene a summit of federal, state, regional and local experts on Monday afternoon, April 29.
Those attending the brainstorming session were welcomed by Hinsdale County Administrator Jami Scroggins, after which the meeting was informally emceed by Drew Petersen who is the State of Colorado’s Regional Emergency Manager based out of Gunnison.
Petersen, who was a familiar face in Lake City during the March avalanche emergency, briefly explained increased concern as the result of runoff from heavy snowpack combined with an immense amount of tree debris which has the potential to clog the stream and back up or divert water flow.
Petersen referenced the goals of this initial meeting, noting “We have to figure out what we have” and, ultimately, the authorities who are responsible for monitoring and mitigating. “We need to assess the degree of risk and — if the risk is valid — then decide what can be done.”
County Administrator Scroggins added extra emphasis to the word “temporary” in explaining that she is also doubling as the county’s Interim Emergency Manager.
Scroggins stated, “We would appreciate any and all expertise” as she gazed out over a packed audience which included representatives from Colorado Dept. of Transportation, the National Weather Service, Colorado Division of Water Resources, BLM, Colorado Geological Survey, Division of Mining, Safety and Reclamation, Colorado Dept. Local Affairs, and Gunnison Office of Emergency Management.
While water levels are on the increase in both the Lake Fork and Henson Creek with warmer temperatures over the weekend and earlier this week, audience member Scott Morrill, from Gunnison Office of Emergency Management, urged a cautious approach. Morrill stated that in his view “no imminent danger” exists at present. “We don’t want to be the boy who cried wolf,” Morrill stated, “but at the same time we want to be prepared for what may occur.”
Monday afternoon’s gathering was held at Coursey Annex and included a mid-afternoon intermission as
attendees got a first-hand glimpse of an “astronomical amount of snow” and “unprecedented volume of debris,” as described by Commissioner Stan Whinnery on a tour up Henson Creek.
Whinnery stated that the Colorado Avalanche Center has confirmed that avalanches which occurred in the Lake City area in March were the largest in the state both in terms of size and the volume of debris which now, unfortunately, has been deposited directly in the path of higher than normal spring runoff.
“It’s not like we have a luxury of time,” Whinnery continued. He noted that historically the height of spring runoff typically occurs late in June and sometimes into early July. During the flood events in 1983, the highest water movement — 2,730 cubic feet per second — occurred on July 10.
On the Henson Creek tour, participants periodically gasped as they viewed the devastation at a succession of snowslides, starting with the Fanny Fern Snowslide a short distance up the canyon from Lake City, and continuing up stream with stops — and more gasps — at the T-Mountain Gulch and Modoc Slides, both of which downed massive amounts of timber in a cascade which briefly dammed Henson Creek and crossed County Road 20.
In his recap of events, Commissioner Whinnery indicated the recent avalanches on Henson Creek and elsewhere in the county represented an unprecedented cycle perhaps not seen by anyone in living memory. Avalanches which cascaded down into Henson Creek in numerous locales brought down whole forests of aspen and conifer, some of the spruce tree trunks of gigantic proportion and estimated in the 200-300 and even 400-year range. Many of the trees are now in fragmentary condition, according to the commissioner, after being ripped out by their roots and then broken into chunks encapsulated in snowslides ranging in depth from 40’ to 60’.
Commissioner Whinnery stated that Hinsdale County Road & Bridge is now incrementally opening roads on Henson Creek as it works toward Capitol City. The road crew has now opened the CR20 thoroughfare through the Modoc Slide above the Ute-Ulay Mine and as of this week was working its way down through the Klondike Slide — termed by Whinnery the “largest ever seen.” The Klondike Slide is located in a narrow canyon roughly a mile above Nellie Creek. Normally the slide is 20’ to 30’ in width but this year stretches out along the canyon an estimated 600’, in the process covering both the road and creek under 30’ of snow mixed with whole and fragmentary trees.
The county crew’s work cutting through the snow is complicated by the intermixed tree debris. As tree remnants are encountered in the snow, it is labor-intensive for the road crew as an excavator is used to grasp the tree trunk and set it to the side of the road, out of the water course. In the meantime, Henson Creek has continued to flow and brief impounding has now cut a natural channel beneath the snow to continue flowing down the canyon.
Commissioner Whinnery indicated that the county may make an emergency declaration in response to increasing water flow combined with impromptu dams which may occur as a result of tree debris in the stream. A disaster declaration was not passed at the county board’s meeting Wednesday this week but is under consideration and may be made next week.
On Monday afternoon’s tour, Whinnery pointed to tree trunks in the stream above the Modoc Slide which crossed Henson Creek and were already impeding the flow of water. Monday’s tour focused on snowslide debris but also concentrated on natural and man-made obstructions in the stream which could impound water as a result of floating debris.
Several narrow spots in the canyon were highlighted in which the canyon walls and widened road surface have resulted in a “pinching” of the Henson Creek channel. Also of concern, and of especial interest to tour attendees Jason Ward and Scott Cuthbertson with the Colorado Division of Water Resources, were two historic concrete dams on Henson Creek which are located at the Hidden Treasure and Ute-Ulay Mines. Both dams date to the late 19th/early 20th Centuries and were breached decades ago with large holes through which Henson Creek flows.
Concerns raised on Monday, however, are that either or both dams might back up water once again if the breach holes become snagged with floating tree debris.
Cuthbertson, who is with the state engineering department of the Division of Water Resources, stated he would be in contact with owners of the dams — the Ute-Ulay is owned by Hinsdale County and the BLM, the Hidden Treasure dam, near Hard Tack Mine, is privately owned — as the state assesses the degree of danger each dam represents and the potential consequences if water backed up behind the dams.
Following his brief Henson Creek tour, Cuthbertson’s initial assessment was that high water and debris will not be confined to just this year. “This is a long-term event,” he said, adding his prediction that “streams will pond and flood.”
Division of Water Resources is continuing to gather data to be used to develop accurate flood maps which, when completed, will be available to the public.
Concerns over debris build-up backing up water and potentially diverting the flow were also expressed in terms of multiple bridges which span Henson Creek above Lake City, including the BLM footbridge accessing Alpine Gulch and two private bridges in the vicinity of the Fanny Fern.
Monday’s tour extended into Lake City where Gunnison CDOT Supervisor Justin Mangum said he was not concerned over debris impacts to the Gunnison Avenue Bridge on Highway 149. Mangum indicated that the CDOT crew would closely monitor the bridge for snags and promptly remove any accumulation of debris.
A Highway 149 CDOT bridge which was mentioned as vulnerable to debris buildup is located north of Lake City in Gunnison County near the Norsworthy and Foran ranches. Local CDOT supervisor R.E. Hall said that the concrete highway bridge would be susceptible to scouring in the event of heavy debris buildup and will be closely monitored this spring.
Below the Gunnison Avenue bridge in town, Town of Lake City has two foot bridges which cross Henson Creek at Henson Street and, below that, the Lake Fork River at 5th Street, with a major town thoroughfare being the lofty 8-1/2 Street bridge leading into the Ball Flats.
Lake City Town Manager Caroline Mitchell was on Monday’s tour and expressed her concern that several of the town bridges, especially the Ball Flats Bridge, serve both pedestrians and traffic, and are also installed with conduit for electric cable serving various parts of town.
Town Manager Mitchell was questioned on the town’s water and sewer infrastructure, both of which could be impacted in the event of flood. The town’s main water wells are located at the mouth of Henson Creek and in Memorial Park in Wade’s Addition, while the water treatment plant is located north of town adjacent to the Lake Fork River. Mitchell said that the town has been in contact with Colorado Dept. Public Health & Environment in terms of both water wells and sewer plant.
A constricted area of the Lake Fork which was also toured on Monday and cited as an area of concern was a portion of the stream just below Second Street. A log jam against cliffs in this area could divert water flow onto the opposite bank and a row of houses which did not exist during the last high water in the early 1980s. In the 1984 flood, Commissioner Whinnery succinctly noted, the area now occupied by the houses was under water.
Reassembling in Coursey Annex for a recap, Regional Emergency Manager Drew Petersen identified areas of concern in the event of flooding and the agencies which would be involved, as follows:
Alerts/Warnings – Hinsdale County, Town of Lake City, National Weather Service, Hinsdale and Gunnison Emergency Services. In terms of flood response, Scott Morrill, Gunnison County Office of Emergency Management, referred to the fact “there are so many variables which we don’t have control over… what we do have control over is communications and informing the public what they need to be ready for.”
A public information meeting on the potential of flooding will be scheduled, and periodic press releases will be issued.
Aldis Strautins, for the National Weather Service offered to draft the template for a weather alert customized to the Lake City area. Alerts and watch notifications would be based on weather data, including factors such as forecast rain events, but that in order for alerts to be effective, Strautins said he must be advised locally on changing factors.
Ongoing Monitoring and “Trigger Points” – Colorado Geological Survey, RWEACT, National Weather Service, Colorado Division Water Resources (dams).
Debris in River – removal of the debris is often not feasible due to geographical conditions limiting access. When removal of jams is possible, Hinsdale County, the Bureau of Land Management, and Colorado Dept. of Transportation were identified as the agencies best able to respond.
Stability of Dams – Division of Water Resources
Mine Reclamation – Colorado Division of Mining, Safety and Reclamation. Tara Tafi stated that there is no indication of water contamination as a result of avalanches or high water to date. She referenced the Henson Creek Mine Waste Repository above the Ute-Ulay Mine, portions of which are now covered by remnants of the Modoc Snowslide. The repository is not impacted by the snowslide, she said, because of heavy concrete which was poured to cap the mine tailings and waste rock.
Concrete covering mine tailings down stream at the Ute-Ulay Mine is less thick, she added, and should be monitored in the event water backed up onto the mine site.
Bridges – Colorado Dept. of Transportation, Town of Lake City, Bureau of Land Management, private landowners.
Caroline Mitchell asked for Colorado Dept. of Transportation expertise reviewing the status of the town’s 8-1/2 Street bridge, including a review of the bridge’s construction plans.
Town Water/Sewer Infrastructure – Town of Lake City, Silver Thread Public Health, Colorado Dept. Public Health & Environment. Town Manager Caroline Mitchell said that for the town’s principal water wells, a switch to generator power is already installed at the Henson Creek well and a generator switch will be installed for the Wade’s Addition well.
Drew Petersen ended Monday’s meeting by urging attendees to “go home and ponder the situation.” In final comments from each of the agency representatives attending the meeting, the consensus was “we’re here to help.”
Commissioner Whinnery thanked representatives from agencies attending the meeting. “It’s a problem,” he summed up, “with no easy solution.” On a bright note and with a rare touch of humor on Monday, he noted “We’ll get through this thing… it will be good if everyone here today takes home a load of firewood, preferably out of the river.”
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