Waiting for run-off

Communities preparing for potential high water

With record amounts of snowfall still on the ground from this winter and temperatures on the rise with the coming of spring, many Gunnison County residents are taking precautions against possible flooding. 

The Town of Crested Butte and Gunnison County hosted a flood awareness meeting on Wednesday, April 9, to a standing-room-only crowd at the Crested Butte Town Hall.
Gunnison County emergency management coordinator Scott Morrill began the meeting, saying his intent was not to overly alarm citizens, but rather to educate about the causes of floods and precautions that can be taken to protect life and belongings in a flood. “We’re not here to be the boy that cried wolf,” Morrill said. “None of us know what is going to happen this spring.”
However, in light of the tremendous snow loads, Morrill said, local governments were taking precautions and citizens should, too.
Morrill invited several guests to speak. John Scott, a district conservationist for the Gunnison area with the National Resources Conservation Service (NRCS), explained how snow and weather factors could contribute to flooding, and related a historical record of high snow and flood danger years.
Next, Arden Anderson, a volunteer disaster coordinator for the Gunnison County Red Cross, spoke about personal safety around floodwaters, ways to prepare one’s property to prevent serious damage from likely floodwaters, and other good tips for survival in case things get bad.
Crested Butte building and zoning director Bob Gillie, town manager Susan Parker, and chief marshal Tom Martin were all on hand to discuss flood strategies for the town of Crested Butte. Gillie also gave an overview of the town’s likely flood zones and factors that could cause flooding in town.
Part One: The Water and the Weather
Compared to last season, this winter probably seems like the most epic to date; but compare it to the last 50 and it’s a different story. Scott’s presentation focused on the wealth of data that can monitor the local snowpack and help predict flood scenarios.
There are three key websites that have public access to real time information and historical records: www.co.nrcs.usda.gov, www.usgs.gov, and www.noaa.gov.
Scott said the majority of data needed to predict runoff comes from SNOTEL (snow-telemetry) measuring sites, which are automatically updated every hour. Real-time information from these sites can be observed on the NRCS website, the first in the list above.
Scott said one important piece of information is the total amount of snow in the area. For instance, the BUTTE measuring station, located near the Twister lift on Crested Butte Mountain, measured 62.2 inches of snow on Tuesday, April 15. On April 9, the date of the meeting, the depth was 68 inches.
Another sensor on top of Schofield Pass reported a snow depth of 127 inches on April 9. Scott said this was the deepest reading in the state.
The site also gives the average date of the peak snow total, which is April 9 in Crested Butte.
Next, Scott explained a snow-water equivalency graph, a measurement of the amount of water in snow. He said in terms of snow-water equivalency, Crested Butte is still trailing behind years such as 1984 and 1995, two heavy snow years that caused flooding danger and significant runoff. In 1984, sections of the city of Gunnison flooded, but Crested Butte did not.
On the National Oceanic and Atmospheric Administration (NOAA) website, one can find historic snowfall totals directly from municipalities. As of April 9, Scott said, the snowfall total in town was 217 inches. He said there were many times in the past when the snow total was above 300 inches in town and due to other weather factors there was no flood danger (see chart).
But aside from the amounts of snow and water, Scott said a big factor is temperature. The main concern is if it gets warm faster than normal, especially when nighttime temperatures stay above freezing. “We want warm days, but we want it to get cold at night. You want that fluctuation so the snow melts evenly,” he said.
Morrill said NOAA was predicting slightly cooler than average temperatures and average precipitation for the rest of April. For May and June Morrill said it flips, and NOAA was predicting higher than average temperatures and less than average precipitation. “If it warms up quickly and stays warm that’s what could cause some problems for us… It’s all up to the weather,” he said.
Finally, the United States Geological Survey website provides information about river flows.
When the Gunnison River flooded in 1984 it peaked in early May, Scott said. The river normally peaks toward the end of May, and sometimes even in June.
But for Crested Butte, at the headwaters, the peak often comes earlier. Scott said the biggest concern for the town of Crested Butte was Coal Creek, but the creek does have one saving grace—because Coal Creek runs east to west, the snowmelt occurs predominately on one side before the other (south-facing first), so runoff won’t rise as steeply as on the Slate River, which runs north to south and receives equal solar exposure on both banks.
Part Two:
Chokepoints
The last time the town of Crested Butte placed sandbags to hold back a flood was in the spring of 1995. Building and zoning director Bob Gillie said long-time residents thought it was silly. “The old timers were laughing at us,” he said. “There is no history the town has ever flooded in the past.”
While waters reached right up to the brim of Coal Creek that year, there was no flooding. Gillie said the town conducted a flood plan study in 1982.
That study identified a problematic area in the alleyway between Elk Avenue and Sopris, and First and Second Streets, where Coal Creek makes an artificial turn between several buildings.
Gillie said the concrete and stone walls of the creek are strong enough to handle a full river, but the designed capacity is the issue. At that section, the creek can handle 900 cubic feet of water per second (CFS) without flood issues. Gillie said the creek reached 800 CFS in 1995.
When the water starts getting dangerously high, Gillie said sandbags would likely be placed along the creek banks. “Our first plan is to keep the water in the creek,” he said.
If water starts coming over the brim, Gillie said the town’s next course of action would be to divert the water from the choke point, through the small alley next to the Powerhouse building, then across the street and back into Coal Creek behind the Timberline Restaurant building.
Resident Jim Starr asked about the condition of the town’s cobble retaining walls, which are secured by woven wire baskets along Coal Creek.
Gillie said, “We’ve done a little re-weaving, but there’s nothing I’m really concerned about in terms of basket failure.”
Gillie also said a number of improvements have been made to the creek to make it better than the conditions studied in 1982.
He said one concern the town would watch for in a flood situation is bank erosion on the creek’s natural banks, but that becomes less of an issue as the creek progresses through town. “When we get below Totem Pole Park, the whole character of the creek changes,” Gillie said.
Morrill said, “One of the things we have identified as a potential issue (in Crested Butte) is debris.” He said in previous high water years there have been lots of branches and other debris built up on the banks.
Gillie agreed. “We’ve had issues with debris in the past in town,” he said, citing debris caught against the bridge that crosses Coal Creek on First Street. He said debris becomes a magnet for more debris—once an area is clogged with a piece of debris it is easier for other pieces to accumulate.
Gillie said when water levels get high the town will stage a backhoe near the first block of Elk. He said the Marshal’s Office would be responsible for checking the creek for obstructions, and when water levels are high the town will have personnel on call 24 hours a day to clear obstructions.
If water does make it onto the streets, Gillie says it’s not too big an issue. He said a street like Elk Avenue can handle nine CFS of water. Gillie said if water were to start flowing down the streets it probably wouldn’t put property in danger, since most homes are at least a foot above street level.
One resident asked where the water would go once it was on Elk Avenue. Gillie said if it wasn’t immediately rerouted the water would probably make its way through the Four-way Stop and into a ditch near Rainbow Park.
Gillie said he had heard other concerns from residents on the east side of town. “A lot of that is new development since we’ve had a high-water threat,” Gillie said. He said he wasn’t concerned. “There are a lot of low-lying wetlands out there that can absorb a lot of water… I don’t think we will see water backing up out there with the Slate (River), but again there are things like debris that can play with that,” Gillie said.