Emergency Watershed Protection Measures in Highly Unstable Terrain on

The Blake Fire burned about 730 ha of mature timber on the west slope of South Fork Mountain in northwestern California. Many steep innergorge and landslide headwall areas burned very hot, killing most large trees and consuming much of the large organic debris in unstable drainages. This created a potential for adverse effects on downstream fisheries from landsliding and the release of sediment formerly retained behind large organic debris. Emergency rehabilitation focused on enhancing channel conditions by falling and bucking downed logs and dead trees and by salvaging dead "high-risk"-trees that could displace soil directly into these drainages by toppling or sliding. Straw bales were wedged behind "replacement" logs to promote retention of landslide debris and other sediment. Current field observations indicate that some of these emergency measures have been effective in the short term. Further data collection and analysis will be needed to evaluate long-term effectiveness. The Blake fire was started on August 30, 1987 by a lightning strike on the west slope of South Fork Mountain in northwestern California (Fig. 1). It burned approximately 730 ha of National Forest land between 1000 and 1700 m elevation, and killed about 250,000 m (60 MMBF) of timber worth an estimated 6 million dollars. Although small compared to other California fires, the Blake fire burned hot and in very unstable terrain. Approximately 160 ha burned at high intensity, killing all vegetation and consuming virtually all protective litter. Another 285 ha burned at moderate intensity, killing the trees but leaving a protective ground cover of unburned duff and subsequent needle fall. The remaining 285 ha burned at low intensity, with scattered trees dying during the first year. Some of the hottest fire burned in unstable drainages where much of the large organic debris was consumed. Sediment production from these tributary drainages can Presented at the Symposium on Fire and Watershed Management, October 26-29, 1988, Sacramento, California. Forest Geologist and District Earth Science Coordinator respectively, Forest Service, U.S. Department of Agriculture, Six Rivers National Forest, Eureka, Calif. adversely affect anadromous fish habitat in Pilot Creek and the Mad River.