Las Vegas has issued an unusual traffic warning: If you live in the northwest valley, downstream from Kyle Canyon, watch out for super mud.
In a bulletin issued Thursday, city officials cautioned motorists to avoid roads flooded with “a black, mucky combination of water, ash and soot” that could wash down from the Carpenter 1 Fire scene, should it rain in the coming days.
The mixture can be as slippery as ice, the city warned.
The forecast for the coming week includes a chance of thunderstorms almost every day.
Rain on the mountain last week washed debris and ash from the wildfire onto parts of Grand Teton Drive, Farm Road and Tenaya Way. City crews have been working to mitigate the problem ever since, but “flows of ash and soot will be unavoidable” in the event of a heavy downpour, the city’s bulletin said.
City officials are particularly worried about flooding and mud on Grand Teton from Durango Drive to Rainbow Boulevard and on Shady Pines Drive between Durango and El Capitan Way.
The potential for muddy flooding in that part of town would be much worse if not for a detention basin built to catch runoff from Kyle Canyon.
“There’s probably two or three feet of soot in the bottom of that basin” from last week’s runoff, said Steve Parish, engineering director for the Clark County Regional Flood Control District.
What flooding there was came from water flowing out of the detention basin and down streets not yet equipped with underground storm channels, Parish said.
The U.S. Forest Service has assembled a Burned Area Emergency Response team to assess and, where possible, address the risks of mountain flooding, mud slides and erosion as a result of the almost 28,000-acre wildfire.
Mary Moore, a hydrologist for the team, said the fire may have dramatically changed how much and how quickly stormwater flows off the range.
And what about that mud?
Moore said soot tends to bond with water and certain soil particles, forming a kind of fine-grain slurry. “That ash is super slippery.”
Contact reporter Henry Brean at email@example.com or 702-383-0350.