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more photosODOT employee Tony Sarmento, 55, of Sisters, sets up cones to close U.S. Highway 20 near Camp Sherman Road on Thursday morning after another avalanche at Hogg Rock.
Andy Tullis / The Bulletin
‘A classic avalanche scenario’
By Kate Ramsayer / The Bulletin
Published: February 01. 2008 4:00AM PSTSantiam Pass remained closed late Thursday night after snow rushed down the slopes near Hogg Rock early Thursday morning and covered the roadway.
With more snow falling throughout the day and evening and an unstable snowpack, the Oregon Department of Transportation took the unusual step of closing the mountain pass overnight.
“We rarely have to keep it closed overnight,” said Joe Harwood, public information officer with ODOT.
While ODOT occasionally has to close the road for an hour or two because of slides that cover U.S. Highway 20, the last time it was closed overnight was eight or nine years ago, he said.
But this year has been an unusually heavy snow year, with more than 12 feet of snow falling on the pass since Dec. 1. And the recent storms have made the area near Hogg Rock very prone to slides, he said.
“What you have is a classic avalanche scenario going on here,” Harwood said.
ODOT has closed the pass seven times since 1996, according to The Bulletin’s files, although one closure stemmed from rainfall and flooding. In 1999, it was closed for about 13 hours.
In the past few days and weeks, several feet of snow have fallen, Harwood said, and cycles of thaws and freezes have created an icy layer in the snowpack.
When new, wet snow falls on that, the snow is unstable, he said.
“It seems like we have a heavy snow year every five or six years where we get several slides over the course of the winter,” Harwood said. “This is definitely a heavy snow year. We’ve had just the perfect type of weather for slides.”
In addition to the weather, the geology of the area contributes to slides. Many of the steeper parts of the Hogg Rock area have a slope that is between 30 degrees and 45 degrees, which is where most avalanches occur, he said. And the rocky slopes have few trees to act as natural anchors to slow the rushing snow.
The department has tried to control slides over the years with tactics like air blasts, but those haven’t been effective.
Road managers in other areas shoot artillery at mountains to trigger controlled slides. Because Hogg Rock is made up of loose rocks and boulders, “if you shoot artillery at it you’re going to bring down the whole mountain,” Harwood said.
The agency is looking at other ways to remotely trigger avalanches and control the slides at the spot, but those discussions are in the early stages, he said.
“Given the unique geologic challenges that we see at Hogg Rock, we’re just really limited in what we can do here,” he said.
Hogg Rock’s namesake
Col. T. Egenton Hogg, namesake of Hogg Rock, was quite a character, said Jean Nave, co-founder of the Sisters Country Historical Society.
“He was involved in lots of things, he was your real wheeler-dealer, investor entrepreneur,” Nave said.
And one of his projects was a railroad that he planned to build from Ontario to the ocean. Part of it, from Yaquina to Corvallis, was built, and workers started on a section in the Santiam Pass area.
But the railroad enterprise failed and the two sections were never connected. Still, the remnants are visible on Hogg Rock, she said.
“If you are very quick in looking up, and there’s no snow, you can see a very small section, a ledge where there’s a crook in the mountain where the rail bed was,” Nave said.
But it might not be there for much longer, she said — avalanches and rock slides are eroding it away.
The origins of Santiam Pass
When Santiam Pass was simply a wagon trail, settlers wouldn’t even consider going over it during the winter, said Jean Nave, co-founder of the Sisters Country Historical Society.
“They didn’t even want to do it in the spring or late fall because of getting caught up there,” she said. There’s even a story of a woman coming over the pass just before the Fourth of July having to camp in deep snow near the Cache Mountain toll station.
The route now followed by U.S. Highway 20 was originally a path that American Indians took over the mountains, following game trails, she said. Early settlers then turned it into a wagon trail, and it wasn’t until 1939 that the road was actually completed.
The route now known as Santiam Pass was previously called Wiley Pass after an early settler, and was also called Hogg Pass for a while, according to Phil Brogan’s book “East of the Cascades.”
Kate Ramsayer can be reached at 617-7811 or at kramsayer@bendbulletin.com.
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