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Mudslide

A 50-foot larch, approximately 3 feet in diameter, was discovered at the top of a debris flow that damaged Durham Creek Road in three places and sent a sediment plume into the Blackfoot River in July. The debris flow was as high as 15 feet in some places.

The Blackfoot River above Johnsrud Park looked like chocolate milk Tuesday afternoon.

The color was similar to what the river looked like in late July, after debris flows in the area burned by the 2017 Rice Ridge fire ended up sending a sediment plume into the stream. That was blamed on a microburst of rain that let loose a mix of mud, rock and trees up to 15 feet tall in places, temporarily damaging Dunham Creek Road in three places.

On Tuesday, Kate Jerman with the Lolo National Forest said they didn’t have any slides reported over roads in the Seeley Lake Ranger District, but are closely monitoring the Lodgepole drainage, which includes Dunham Creek Road. They’re also watching the adjacent Spruce Creek, Dunham Creek, and Lodgepole Creek drainages.

Both Jerman and Christie Oschell with Montana Fish, Wildlife and Parks said they can’t say with certainty what’s going on with the Blackfoot’s change in color. But Jerman said field observations indicate the color probably isn’t coming from the area burned in the Rice Ridge fire, at least not entirely.

“It could be a combination of sources that are contributing to the downstream color; the recent storms may have reactivated sediment deposition from the previous debris flow or the increased water flows from the storms could be causing bank erosion within the middle reached of the mainstem Blackfoot River,” Jerman noted in an email to the Missoulian. “We can’t say how high it goes up at this point either, and it is unclear if there is an impact to the fisheries.”

Bob Nester with the National Weather Service said the East Missoula area received about 1.5 inches of precipitation between Sunday and Monday afternoon, and East Bonner took in another one-third of an inch Monday night in about 10 minutes.

Meanwhile, Bigfork saw a 24-hour total from Sunday to Monday afternoon of 3.25 inches; Swan Lake took in 3.28 inches and Seeley Lake had 1.85 inches during that 24-hour period.

“So it’s safe to say that area (near Johnsrud) had 1 ½ to 2 inches,” Nester said. “Missoula’s had 1.65 inches so far for the month of September, and as of today it’s the wettest start to September since 1897.

“Kalispell has had through today 2.51 inches for the month of September, which is a record so far for the first 10 days of the month; it’s beaten the record by over half an inch” since precipitation was first recorded in 1893.

Nester said the forecast calls for showery conditions, but nothing like the system that parked over the greater Missoula area for the past week. Wednesday should see a few showers, but the skies are expected to clear as we move toward the weekend.

“But there’s a wet system in the Seattle area that’s been sitting over them for a couple of days,” Nester said. “The computer models are inconsistent in showing the same thing, but it doesn’t look like it will be all that wet. … At the earliest, Saturday and Sunday we might get impacted by some precipitation, but nothing like last week.”

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