BAER report summary completed; Work begins to stabilize Caldor burn area
SOUTH LAKE TAHOE, Calif. — After spending weeks assessing the Caldor Fire scar, the U.S. Forest Service on Thursday released the Burned Area Emergency Response summary and the team has begun working on stabilizing the area.
With the fire officially 100% contained, stabilization efforts are coming none too soon, as a historic storm is forecasted for this weekend through early next week.
“Forest Service BAER assessments focus on imminent post-fire threats to life and safety, property, critical natural resources and cultural resources on National Forest System lands,” the summary states. “Threats include determining where post-fire rain events could increase runoff and flooding, erosion and sediment delivery, debris flows, and high- risk areas for the spread of invasive weeds.”
The burned area consists of 1,735 miles of streams, 208 miles of trails and 1,051 miles of roads.
BAER crews began work on Sept. 8 on the western portion of the fire. According to the summary, “the initial team consisted of soil scientists, hydrologists and geologists focused on mapping soil burn severity levels using an initial BARC (burned area reflectance classification) satellite imagery generated map that compares pre- and post-fire images.”
“Additional BAER specialists, including geographic information systems specialists, road engineers, aquatic and terrestrial biologists, archeologists, botanists, and recreation managers engaged a few days later in order to assess imminent post-fire threats to human life and safety, property, and critical natural and cultural resources,” the summary continued.
The first step in the assessment is to identify soil burn severity. According to the summary, “fire damaged soils have low strength, high root mortality, and increased rates of water runoff and erosion.”
Of the 218,952 acres assessed, 13.1% showed signs of high burn severity and 41.2% showed signs of moderate burn severity.
As far as erosion hazard goes, much of the burned area has a low erosion hazard rate (46.3%), while only 4.3% is rated very severe and 23.5% as severe. The erosion risk is predicted to be higher in the Cosumnes River basin than in the South Fork American River basin and the Lake Tahoe Basin.
However, for the Lake Tahoe Basin, the risk only remains low if the precipitation received this year is snow which does not erode soil, rather than rain.
Efforts to stabilize the soil are already underway. Using burned trees, teams have stabilized 2 acres of soil along Silver Fork Road.
“Two fallers are falling small trees in areas where high dispersed camping concentrations on sensitive soils have led to chronic erosion and loss of soil productivity,” said Jennifer Chapman, public affairs officer for the Eldorado National Forest. “The treatments are to replace burned vegetation that limited the extent of effects.”
While this area is already prone to rock slides and debris flow, the threat will be exacerbated because trees and vegetation that normally provide natural stabilization and barriers have burned.
“Removal of vegetation by the fire has exposed and weakened soils, changing hydrophobic conditions. Also, rocks on slopes have lost their supportive vegetation,” the summary stated. “These post-fire conditions in addition to ample supply of woody debris will exacerbate debris flow events occurring in this burn area.”
Vegetation recovery takes years to decades to be completed. For areas of low burn severity, it could be 2-15 years before soil cover and vegetation structures fully return, while in areas of moderate to high burn severity, it could take 50-100 years.
In the meantime, Lake Tahoe water quality is of concern. Sediment and ash have a risk of flowing into the lake via Trout Creek to Upper Truckee River.
The BAER assessment report needs approval from local Forest Service Supervisor’s Offices, Regional Offices, and the Washington Office. However, because of the severity and complexity of the fire, the BAER team requested work to start in the area while the report was being completed.
Chapman said several activities are being completed and “demonstrate what the BAER Team is accomplishing to increase safety and to protect human life, property, and critical natural and cultural resources on National Forest System lands.”
In addition to the soil stabilization work that’s been completed, work has been done to stabilize roads and clear hazards.
“Ten hazardous waste areas were stabilized where immediate risk to water bodies was identified,” Chapman said. “The 10 areas consist of nine recreation residences in the Fir and Bryant tracts and the Capps Crossing shed. Straw wattles were installed downslope of the hazardous waste so that hazardous material near water bodies would be filtered by the wattles.”
Recreation residences are privately-owned homes located on Forest Service land.
Pressure treated timber from the Capps Crossing bridge burned and fell into the creek during the fire so the Lake Tahoe Basin Management Unit road crew removed the treated timber from the creek and removed both the burned and the remaining unburned timber from the bridge deck.
“Related to the work of the BAER team, the Eldorado National Forest is also working with the Environmental Protection Agency to remove emergency hazardous waste from burned structures in the recreation residence tracts that could potentially contaminate watersheds,” Chapman added.
Crews have also begun felling hazardous trees around recreation residences and high public contact areas. They’ve also removed trees from Sierra-at-Tahoe.
Work on clearing roads has also been a priority.
“Starting at the higher elevation roads, road maintenance work is focusing on opening all the drainages on affected roads before winter,” Chapman said.
Focus has been paid to the culverts, ditches, and shoulders on the Mormon Emigrant Trail and roads around the North-South Road (10N83) as well as on that road itself.
There is still a lot of work to be done. In addition to continuing to clear hazardous trees and materials, the BAER team has recommended several actions be taken, including spreading chemical herbicide to prevent the spread of invasive weeds in burned areas, protecting Sierra Nevada yellow-legged frog habitat by installing in-channel wood treatments to minimize sediment delivery and protecting trails and cultural sites with straw wattles and sand bags.
With the winter storms on their way, the Forest Service is continuing to emphasize remaining out of affected areas and to be extra cautious while traveling during storms.
To read the full summary, visit https://inciweb.nwcg.gov/incident/7842/.
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