Hidden Wildfire Monitoring Report Sequoia and Kings Canyon National Parks, California Prepared by Lauren Miller For Firefighters United for Safety, Ethics and Ecology November 2008 The Hidden Fire started as a lightning strike north of Ash Mountain in Sequoia National Park, California on September 10th, 2008. A lightning cell moved through the park and started three fires; the one that wasn’t caught was the Hidden Fire. Although the fire occurred in a wilderness area at 5-6,000 feet of elevation, it was near private lands and below the Generals Highway and park developments along the highway. Due to the existence of private property and developments, Park Service managers decided to aggressively suppress the fire. The fire was burning in heavy and dry mixed conifer (Douglas-fir and ponderosa pine) and steep terrain with cliff areas. Due to these conditions, a high growth potential, undesired fire behavior, smoke impacts and the potential for the fire to spread into developed areas were primary management concerns. Initial attack operations were indirect due to steep and inaccessible terrain. As smoke was detected late in the evening on the 10th, park managers did not want firefighters to engage in suppression operations without first scouting the country in daylight. Firefighters were pre-positioned and ready to engage on the 11th. Accessing the Hidden Fire required about four and a half miles of hiking across country in heavy fuels and difficult terrain. A helispot was cleared before firefighters could be flown into the area. The difficult and slow access allowed time for the fire to grow before containment could be effective. The area was under a Red Flag Warning for hot and dry conditions that allowed for the fire to continue growing for about three days, with evening temperatures allowing the fire to burn through the night. Rollouts crossed firelines at night and firelines were lost. The Park eventually brought in a Type 2 Incident Management Team to help contain the fire. Although the fire was burning in wilderness, the west flank of the fire was a containment priority due to private lands on that side. Rollouts on the west flank would have caused the fire to spread into private land and populated areas where the Park Service did not want it to enter. The western flank was suppressed first as the Park Service had more flexibility on the eastern flank. Eventually the east flank grew into a cliff band where firefighters could not safely engage and fire managers decided to use indirect fireline, including using ridges and parts of the Generals Highway. Burnout operations were performed to remove fuels and create strong firelines in advance of the main fire. For the first four to five days during initial attack operations, retardant drops totaling 263,000 gallons of Phos-Chek brand retardant were used on the head and flanks of the fire to try to prevent spread; a majority of the drops occurred on the western flank. There were about 60 firefighters in position to take advantage of the retardant drops, but the fire often burned through retardant lines. The retardant drops did not have the desired effect on the fire’s intensity or rate of spread; weather conditions at the time were very hot and dry and a Red Flag Warning was in effect. Once initial attack operations concluded and catching the fire small became unlikely, fire managers began planning an extended strategy utilizing other containment options and retardant use was suspended. The drops occurred in wilderness, in an ecologically sensitive area near the park cave networks. Much of the surface water in the area becomes a below ground stream system that feeds these cave networks. The Park Service Caves Management Specialist and Chief or Resources expressed concerns to fire managers about the use of retardant in this watershed due to the presence of an aquatic isopod that is endemic to this cave system, as well as an endemic spider species. Once aware of this concern, fire managers discontinued retardant use. Park Service managers are almost certain that significant retardant drops did not occur in the cave network or contributing surface water systems and have submitted a monitoring request to determine if retardant was dropped either into the cave network or other streams. Retardant impacts are the major long-term concern for Park managers regarding the Hidden Fire. The effects of the fire itself are not anticipated to be a problem for the caves, but if retardant did enter the hydrological system the impacts on the endemic species are a significant concern. About 12 linear miles of fireline was constructed during containment efforts. The Park Service had directives to not put in fireline constructed by heavy equipment or in sensitive natural areas such as old-growth stands, endangered or threatened species habitats or fragile soils. A lot of the initial handline was compromised due to rollouts and upslope fire runs. Most of the fire area had not seen fire since 1926; the historical fire return interval is about 15 years and it is very steep terrain with significant fuel accumulations. Many interior firelines were constructed and then breached by the fire and abandoned. There is a potential that some old-growth trees were dropped for helicopter landing zones, but this is yet to be confirmed. If there were any old-growth snags determined to be a safety hazard for firefighters in the direct area, these trees would have also been felled, as is standard procedure to ensure firefighter safety. The biggest firefighter safety concerns were steep terrain and snags. A Burned Area Rehabilitation plan has been submitted for areas affected by suppression operations, including hiking trails, firelines, helispots and spike camps, with a primary objective of mitigating erosion. The Park Service does not use grass seed or straw for slope stabilization. Significant fireline rehabilitation has already occurred as part of the mop-up phase of the fire. Park managers employed Minimum Impact Suppression Tactics, taking advantage of terrain and the landscape whenever possible. Burnout operations were integral to containing the fire. Of the 12 miles of handline constructed, about 6 miles were strengthened with burning operations, mostly on the eastern flank. About 100-200 acres were added to the fire area as a result of burnout operations; indirect attack was the only option once the cliff bank on the east flank was encountered. Firing operations were mostly conducted at night when cooler temperatures and down canyon winds could be taken advantage of. They were carefully planned, as during some firing operations weather conditions were hotter and drier than what managers would allow under prescribed fire parameters. Some firing operations also occurred under cooler temperatures and higher relative humidities, with favorable down canyon winds that pulled fire in the desired direction. The fire went from burning under hot and dry conditions, to conditions that were nearly too cold and wet to burn, then it became hot and dry again. Managers were able to take advantage of the cooler windows to burn under. The primary ignition devices used were driptorches, however on a cooler and wetter day aerial ignitions occurred in the interior using plastic sphere dispensers, or ping pong balls. The expected fire behavior of firing operations was in alignment with what was observed, however the burnout may have burned too cool. The cooler days affected the burnout’s consumption accomplishments. Within the burned area overall, 98% was low intensity fire with small pockets of high intensity; the observed fire behavior was largely favorable. Most slopovers that occurred resulted from either rollouts or spotting. On the southern flank there were multiple rollouts; on the northern flank there was a hot and dry day when the fire aligned with the wind and made a run that resulted in spotting. Fire managers would have liked to have fire enter the park’s sequoia groves; sequoias are adapted to thrive in low- and moderate-intensity fire, but the fire did not significantly spread into the groves. If a high intensity head fire was anticipated to enter the sequoia groves, fire managers would have ignited a backfire which would have allowed them to define and moderate the type of fire that entered the groves due to their ecological and cultural value. The observed fire behavior did not damage the sequoia groves. The Wildland Fire Decision Support System planning document gives managers the option to designate important areas where fire behavior needs to be monitored and tactics adjusted to accommodate ecological values. Park Service managers had written into the plan that burning operations would occur in the grove to ensure desired fire behavior if the situation arose. The area’s historic fire regime was considered in determining management objectives. The burned area had a high fire return interval departure (FRID); it had missed 3-5 natural fire cycles. For most of the eastern perimeter, prescribed fires had occurred in the 1980’s and fuel accumulations were less of a concern there. About 80-90% of the perimeter hadn’t burned since 1926 and there were heavier fuel accumulations there. Thinning had occurred within the past 5-10 years along the Generals Highway section of the fire perimeter where burnout operations were performed. The bulk of the perimeter was in wilderness; no prior treatments had occurred there. The most significant fuel reduction objective that was accomplished by the fire was a FRID conversion from a high FRID area to a restored natural cycle, which is always a desirable accomplishment to fire managers. The observed fire behavior was in alignment with what was desired, with just a few high intensity areas, and the risk of an unnatural fire occurring in the fire area was reduced. Park Service managers were concerned about the potential for high intensity behavior and significant growth with weather conditions being hot and dry. The initial attack efforts had helped to reduce the potential for significant growth, which gave fire managers the chance to manage it on their stated terms and objectives. Figure 1: Hidden Fire Perimeter Map as of September 24nd, 2008. Bibliography Birkholtz, Ann. InciWeb.org. 26 Sept. 2008. InciWeb, Incident Information System: Hidden Large Map. 7 Oct. 2008. http://www.inciweb.org/incident/maps/large/1541/0/. InciWeb.org. 1 Oct. 2008. InciWeb, Incident Information System: Hidden Wildland Fire. 7 Oct. 2008-28 Oct. 2008. http://inciweb.org/incident/1541/. Schweizer, Deb. Telephone Interview. 28 Oct. 2008.
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