BOISE -- All lanes of U.S. Highway 20 north of Mountain Home are back open after a mudslide forced one lane to close Thursday night.

The mudslide was reported to be around milepost 114, which is between Cow Creek Road, Prairie Road, and Anderson Ranch Dam Road.

Elmore County dispatchers report at least one person had to be rescued by boat after Thursday's rainstorm brought soil, mud, and debris rolling down hills onto other nearby roadways. The roadway into Fall Creek, where a number of cabins burned in the Elk Complex Fire, is heavily blocked by boulders and logs.

[Thursday] night for about a 45-minute period starting around 6:30, we had almost half an inch of rain in a very localized area right around Anderson Ranch Dam, U.S. Forest Service spokesman David Olson said.

Olson said there are around 10 mudslides around the dam area and the debris briefly clogged the South Fork of the Boise River, cutting the flow in the area by around 60 percent for a time Thursday night. The flows have since returned to normal.

What's interesting about this storm is it was very localized. So if you go toward Prairie, or if you go toward Pine or Featherville, there is really no impact at all. So it was a very localized but very intense rain storm that created quite a bit of mudflow into the road system, and into the river, Olson said.

The following roadways remain closed Friday, and some bridges are washed out, according to officials.


  • Anderson Ranch Dam Road at U.S. Highway 20
  • Castle Creek Bridge -- washed out
  • Cow Creek Road at U.S. Highway 20
  • Fall Creek Road, including nearby bridges
  • Granite Creek Road
  • Prairie Road to Davison Ranch

The closures do not include staffed roadblocks, so drivers are encouraged to be aware of changing conditions.

The mudslides and flooding are thought to be spurred by area wildfires, including the Pony and Elk fires, which burned in August. With the amount of burn that occurred and the intensity of the burn, there were many people that said this is not an 'if,' but a 'when' situation, and indeed we saw the 'when' already just shortly after the fire was contained, Olson said.

The rain is also causing problems in Boise County.

Campers are being evacuated along Grimes Creek Road where as much as 8 inches of mud covering part of that road tonight.

Authorities are closing Grimes Creek Road at the Clear Creek turnoff -- all the way to Centerville.

There has been one large mudslide along Grimes Creek Road, along with several other smaller slides.

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