Landslide & Flooding Risk Threat Report
Eighteen federal, state and local agencies evaluated land within the Holiday Farm Fire perimeter to identify areas at increased risk of flooding, landslides, debris flow, loss of aquatic habitat, increase in invasive species, and more.
The report, called the Holiday Farm Fire Erosion Threat Assessment and Reduction Team (ETART) Report, is a valuable tool in establishing how fire-damaged soil can change and increase the effects of flooding and landslides for years after a fire.
Below, we will share some of the key areas identified in the report. We encourage McKenzie Corridor residents to review the report or report summary (links below) in addition to our quick overview.
Areas identified as at increased risk of flooding and floating debris:
- Very High Risk to boaters and swimmers in the McKenzie River for floating woody debris and additional “strainers” (woody slightly below the water surface). Debris is already observed in river and volumes are expected to increase.
- Very High Risk to visitors and employees at Blue River Park (picnic shelter, play structure, picnic tables, sports fields and hiking trails) from rock fall and soil erosion from steep hillslopes; open vertical 4 foot diameter culvert (south of ball field – no increased risk due to fire); ballfield backstop is damaged; increased danger of rock fall along walking trail that follows left bank of Blue River. Also, potential for increased erosion and unstable streambanks along Blue River, but with streamflow regulated by dam probably not a major concern.
- High Risk to residents along Gate Creek, adjacent to creek from flooding, debris flow, and erosion. High potential for increased peak flows and flood/debris flow to result in injury or loss of life and impact homes. Two or three homes that survived the fire may be in danger of flooding. Expect increased sediment load to McKenzie River. Bridge looks OK for passing high flows and debris.
- High Risk to occupants in unburned homes along Gate Creek, Goodpasture Road, and Simmonds Creek from hazard trees upslope of occupied structures; from sediment bulked flows impacting riverbanks, erosion, and property boundaries along creek. Some unburned homes remain near the outlet of the confined Gate Creek drainage. Egress for people occupying unburned structures may be trapped by hazard trees during sediment or debris-laden flows during major storm events
Areas identified as at increased risk of landslide, rock fall or debris flow:
- High Risk to life and safety at Lazy Dayz Mobile Home Park, Lucky Boy Road, McKenzie K-12 School in Blue River, Old Scout Road, OR-126, Rough Creek and Rail Creek, Shepard’s Landing and McMullen’s Landing, Simmons Creek – Blue River Bridge, Town of Blue River, Town of Nimrod, and Town of Vida from debris flows, rock fall or landslides. Portions of the communities and/or facilities are built on past debris flow fan deposits.
- Intermediate Risk to life and safety at McKenzie Fire & Rescue Station 16-5 (Nimrod, Local Community) from debris flows, rock fall or landslides. Fire station located downslope of low debris flow hazard where the channel bends in the deposition zone. If debris flow is significant enough, it can avulse channel and deposit material at fire station.
- Intermediate Risk to employees and visitors at Blue River Dam (USACE) from rock fall and accelerated erosion.
- Low risk to life and safety at Ben and Kay Doris State Park, H.J. Morton Memorial Park, Marten Rapids and Thomson Parks, Blue River Community Park, Forest Glen County Park, Gates Creek at Vida, McKenzie Fire & Rescue Station 16-4, School in Vida (K-12), Blue River Dam, Blue River Reservoir, Cougar Dam and Facilities, Cougar Dam Electric Transmission, Leaburg Hatchery, Leaburg Reservoir, Leaburg Dam, and Quartz Creek from debris flows, rock fall or landslides. Portions of the communities and/or facilities are built on past debris flow fan deposits.
The risk categories were assigned based on the probability of damage or loss coupled with the magnitude of consequences. The full report provides detail and context beyond the summary in this email.
Lane County Road & Bridge Maintenance has been active in working to mitigate the increased flooding risks where possible by clearing debris from County-maintained ditches and culverts, evaluating County-maintained bridges for needed repairs, and removing hazard trees from road rights-of-way. Lane County Roads has also moved all County roads within the Holiday Farm Fire perimeter to Priority 1 for winter weather response. They will be monitoring for debris runoff, fallen rocks, and debris build-up at culverts, ditches and storm water drainages. You can learn more about how Lane County prioritizes roads here.
