Southern California Fires
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Mendocino National Forest Burned Area Emergency Response (BAER) Post-Fire BAER Assessment September 25, 2018 RANCH POST-FIRE BAER PHASE 1 ASSESSMENT REPORT SUMMARY The Ranch Fire started on July 27, 2018, and is located approximately northeast of Ukiah, California. The southern half of the Ranch Fire burned area was surveyed and assessed as Phase 1 by a Forest Service Burned Area Emergency Response (BAER) team comprised of scientists and specialists. The Forest Service (FS) is responsible for addressing risks on NFS land. The BAER team evaluated the burned watersheds to determine post-fire conditions, and identify values-at-risk such as threats to human life and safety, property, and critical natural and cultural resources. In addition to these critical values, other threats were also assessed, such as the risk for increased post-fire flooding, sediment flows, rock slides, hazard trees and noxious weed spread. Proposed emergency stabilization treatments are recommended by the BAER team which reduce these potential threats. The Phase 1 BAER assessment team analyzed approximately 191,068 acres with 87,849 acres of Forest Service System (NFS) land, 30,007 acres of Bureau of Land Management (BLM) land, 24 acres of other federal land, 2,484 acres of state land, 78 acres of local government land, and 70,626 acres on private land. Notably, the US Department of Interior (DOI) conducted their own separate but similar (Emergency Stabilization & Burned Area Rehabilitation) assessment for BLM/DOI lands, in coordination and communication with Forest Service efforts. Dominant vegetation types within the NFS burned area include chaparral consisting of mixed-chaparral, Chamise-Redshank chaparral, and Montane chaparral transitioning to coniferous-hardwood forest, including Montane hardwood, and Montane hardwood- conifer. The BAER assessment team’s Phase 1 analysis of the burn area and recommended emergency treatments are documented in a Forest Service Burned-Area 2500-8 Report. This report was submitted to the Regional Forester for the Pacific Southwest Region (Region 5) and the Forest Service Chief by the Mendocino Forest Supervisor for review and funding. The BAER report also provides relevant information that is shared with its inter-agency cooperators to help identify potential threats to lands downstream of the fire. The following is a summary of the BAER team’s Phase 1 burned area assessment for the Ranch Fire: - 19 sub-watersheds were analyzed and modeled to compare pre-fire conditions to post-fire predicted response: East Fork Russian River, Cold-East Fork Russian River, East Park Reservoir, East Fork Middle Creek, West Fork Middle Creek, Middle Creek, Clover Creek, Crabtree Lodge-North Fork Cache Creek, Newman Springs- North Fork Cache Creek, Bartlett Creek, Hough Springs-North Fork Cache Creek, Indian Valley Reservoir, Wolf Creek, Long Valley Creek, North Shore Clear Creek, Clearlake Oaks Shore-Clear Lake, Upper Bear Creek, Middle Bear Creek, and Scotts Valley-Scotts Creek. - There are approximately 180 miles of perennial streams, 433 miles of intermittent streams, and 1,714 miles of ephemeral streams. - There are approximately 119 miles of roads, and 45 miles of trails. - There are about 65,723 (35%) acres of unburned/low soil burn severity, 113,344 (59%) acres of moderate soil burn severity and 12,000 (6%) acres of high soil burn severity. Soil burn severity is the fundamental indicator used to evaluate post-fire conditions. The soil burn severity categories reflect changes in soil properties from pre- to post-fire and are a key element used to identify post-fire threats. The distribution of unburned, low, moderate, and high soil burn severity levels become a baseline for resource specialists to monitor changes in soil-hydrologic function and vegetative response as the burned watersheds recover. Hydrophobic soil conditions are common within moderate and high burn severity areas and rare in the low burn severity areas. High and moderate soil burn severity categories have evidence of severe soil heating and the consumption of organic material; the soil seedbank and water infiltration characteristics are degraded. Natural recovery is slower where the seedbank is affected by heating, or where soil fertility is affected by either organic matter consumption or increased soil erosion. Areas of moderate soil burn severity have viable roots and some soil cover, but may still be vulnerable to erosion on steep slopes. The low to very low soil burn severity areas still have good surface soil structure, intact fine roots and organic matter, and should recover more quickly once revegetation begins and soil cover is re- established. Identified Values-at-Risk, Threats, and Emergency Conditions Thunderstorms have the greatest possibility of generating large runoff and soil erosion events, although they are low-probability events for any given area. If large rain events do occur, the primary values-at-risk within the burned area are human life and safety, transportation infrastructure (roads and motorized trails), cultural resources, and native vegetation communities. The primary threats caused by the fire include 1) increased runoff, which is expected to intensify the first 2-3 years following the fire until the burned watersheds recover, and 2) accelerated hillslope erosion as a result of increased runoff and decreased infiltration rates. High intensity, short duration rainfall may result in downstream flooding and localized debris flows. Additional threats originating from the destabilized hillslopes throughout the burned area include falling trees and road washouts. Emergency post-fire conditions for Phase 1 of the Ranch Fire assessment were identified by the BAER team for the following on-forest values-at-risk: - Human Life and Safety: There is very high risk for forest visitors and to be impacted by rockfall, flooding, landslides, debris flows, and hazardous trees along roads and trails, and at recreation sites. There is also an increased threat to on non-FS property and roads within and downslope of the burned areas from the potential for flash flooding, debris flows, falling rocks, and hazard trees as well as loss of ingress and egress to landowners if road systems are impacted. - Property: There is high risk to FS roads, stream crossings, FS trails, and related infrastructure within the burned area from post-fire impacts of increased water, sediment, and/or debris flows. Impacts include damage to the road and trail surface and drainage features and/or loss of access due to severe erosion of the road and trail surface, or deposition of sediment or debris. There is increased threat of property damage on non-FS property and roads within and downslope of the burned area. The potential for flash flooding, debris flows, falling rocks and hazard trees. - Natural Resources: An increased risk is anticipated to native or naturalized plant communities due to the threat from the spread of noxious weeds. The wildfire created conditions conducive to noxious weed spread and establishment by reducing competition, and exposing bare mineral soil. Post-fire soil erosion will occur to some degree, and should be put in context of this being a natural and dominant geomorphic process in fire-prone Mediterranean climates. - Cultural/Heritage Resources: A high risk is anticipated to critical cultural and heritage resources within the burn perimeters due to the threat of predicted increased flood flows, erosion, sediment, and debris flows as well as the potential for damage from off-trail OHV traffic due to the loss of site protection barriers which protected cultural sites pre-fire. Emergency Stabilization Treatments Treatment Objectives The BAER assessment team’s emergency stabilization objectives for the burned areas are to protect, mitigate and reduce the potential for identified post-fire threats, including increased water run-off flows, soil erosion/sediment yield, loss of road and trail access, introduction and expansion of invasive plant species, and falling burned trees, for: 1. Human life, safety, and property within and downstream of the burned area; 2. Forest Service infrastructure and investments such as roads and trails; 3. Critical natural and cultural resources; and 4. Native and naturalized plant communities from new noxious weed infestations. The following post-fire emergency stabilization measures and treatments have been approved: - Install burned area hazard warning signs to caution forest visitors traveling and recreating within the burned area. - Implement and monitor temporary NFS road, trail and recreation site closures to prevent public access to at-risk areas within the burned area to protect human life and safety. - Implement hazard tree removal and recreation facilities and road and trail work areas to insure safety during post-fire emergency treatments. - Storm-proof and stabilize NFS transportation roads and stream crossings with improved water drainage structures and features to prevent damage resulting from post-fire watershed conditions such as soil erosion, storm water run-off, and public safety hazards to improve the safety of forest visitors and employees. Conduct storm patrol monitoring to ensure stream crossings and road treatments are functioning as intended. - Storm-proof and stabilize NFS trails and trailheads with improved water drainage structures and features to prevent damage resulting from post-fire watershed conditions. Conduct storm patrol monitoring to ensure crossings and trail treatments are functioning as