Two conservation groups are concerned that a landslide near a creek critical for bull trout was partially caused by a U.S. Forest Service road, but the Forest Service says the slide was a natural sloughing process in a valley prone to such occurrences.
The Swan View Coalition and the Friends of the Wild Swan notified management at Flathead National Forest on July 21 of a large landslide that landed in Sullivan Creek, which lies south of the Hungry Horse Reservoir and east of Swan Lake, after finding the slide on July 16.
Keith Hammer, chair of the Swan View Coalition, said the mass amount of earth that fell into the creek would damage water quality of the waterway, which is a critical habitat for bull trout. Forest Service Road 547 lies at the apex of the slide, and Hammer’s group believes poor drainage caused the sloughing.
“This is a road built on an unstable hillside to begin with,” Hammer wrote in a press release on July 24. “Then the Forest Service failed to install enough culverts to drain the ditch, causing runoff to instead perk beneath the road and lubricate this landslide. It was a ticking time bomb.”
However, a July 29 report from Forest Service hydrologist, civil engineer and engineering technician said it was unlikely road drainage caused the slide, and that the valley has had 14 similar slides in a 2.8-mile stretch.
“There were no visual signs of scour or deposition on the road surface, which suggests that no surface runoff was occurring on the road surface,” the report reads. “The ditch is well vegetated with grass and shrubs.”
The slide was likely caused by the river eroding the base of the hill slope, the report concluded.
After the Forest Service released its report on July 29, the conservation groups released their own Aug. 1 response, noting that the groups believe that certain parts of the assessment were incorrect, and that the road likely played a bigger role in the slide than the Forest Service determined.
In an Aug. 4 interview with the Beacon, Hammer said he believes his group and the Forest Service will just have to disagree about the cause of the slide, and now the focus should be on the future of Forest Service Road 547.
“What we want to see from the Forest Service is a recognition that this road is going to finish caving in,” Hammer said. “They need to get in there while they can still get heavy equipment in and get the culverts out.”
Chip Weber, Flathead National Forest supervisor, said there are no immediate plans to perform any such work on the road. It is a Maintenance Level 1 road, meaning it does not require annual maintenance because motorized travel is off limits, but has not been decommissioned.
There is a gate in place blocking vehicles from entering the road, Hammer and Weber noted.
The Forest Service’s primary concern is making sure the road is hydrologically stable, Weber said, and he believes the hydrologist and civil engineer cleared that up with their July 29 assessment.
“It’s not something associated with the road that’s causing this (sloughing),” Weber said. “There’s been thousands of years of this similar phenomenon.”
Weber said keeping the road at its Level 1 status will allow the Forest Service to keep from having to recut the road in the future when it needs access for future Forest Service activities like a timber harvest or tending to young trees.
“Decommissioning (the road) means taking it off of our road system and we don’t want to do that because we think we will need it in the future,” Weber said.
Hammer has previously written to the Forest Service regarding Maintenance Level 1 roads, urging the Forest Service to decommission more roads instead of keeping them as Level 1.
“Sullivan Creek is just one more example of what goes horribly wrong with logging roads,” Hammer said in the July 24 press release.
The slide area was part of a major wildfire burn in 2003, and Hammer said the Forest Service would not have to perform any logging action for decades. Hammer also said his group is not in favor of banning all human access to the area, which is popular for hunters, anglers and hikers, but the Swan View Coalition would like the Forest Service to work quickly on the road before more large slides send it into the creek.
Weber said the Forest Service already conducts assessments of all its roads, and said he is comfortable with the recent analysis of this particular road.