KREMMLING — For some ranchers in Troublesome Valley, the worst impacts of the wildfire that began near there in October might not arrive until summer — or even summers beyond.
Experts say the greatest danger of sedimentation from the East Troublesome Fire will occur during and after a hard rain, especially of an inch or more. That is when the severe soil damage from the fire will cause sediment to wash into the east fork of Troublesome Creek and into a diversion ditch used to irrigate 10,000 acres of hay.
“It’s a real concern for us,” said Kent Whitmer, one of seven ranch owners who get water from the ditch owned by the East Troublesome Mutual Irrigation Co.
Whitmer said he most fears sediment filling the ditch so badly that it overflows.
“That would be disastrous,” he said.
Agricultural and municipal water users will see broad, lingering effects of the 193,812-acre fire.
The East Troublesome Fire, which had been burning east of Colorado Highway 125, exploded on the afternoon of Oct. 21, driven by 70 mph winds. In all, the fire grew 100,000 acres in 24 hours, eventually becoming the second-largest wildfire in the state’s recorded history. The fire was formally designated as contained Nov. 30, although small plumes of smoke could be seen in the golf course area as recently as Christmas Day. All but about 5,000 acres of the fire burned in Grand County.
Denver Water may offer lessons useful to water managers, who will be dealing with impacts from the East Troublesome Fire for years, perhaps decades. Denver Water has struggled with sediment and debris clogging its two major reservoirs in the foothills southwest of Denver. The fires that caused problems for those reservoirs — Buffalo Creek in 1996 and Hayman in 2002 — fried soils, removing their ability to absorb moisture. Sediment has been washed up to 11 miles into Strontia Springs and Cheesman reservoirs, pushed by water during summer cloudbursts.
Denver Water has spent $28 million in reservoir dredging, facilities repair and landscape-restoration projects. It discovered that debris and sediment can travel downstream to cause problems in critical water infrastructure. At Strontia Springs, Denver Water dredged for sediment as recently as five years ago but may need to do so again this year.
“Dredging is very costly,” Denver Water watershed scientist Christina Burri said during the recent post-fire water impacts webinar. Retrieving sediment and debris can be challenging, and then there’s the issue of what to do with the debris. “Do you pile it? Do you burn it? Where can you take it?” Burri said.
The East Troublesome Fire might…