Effects of Backpackers and Stock Use on Wilderness Water Quality in Sequoia & Kings Canyon National Parks

Backpackers and pack animals, primarily horses and mules, may impair water quality in high-use zones of federally designated wilderness areas within Sequoia and Kings Canyon National Parks (SEKI). Impacts include erosion from trails, campsites and grazing sites, which increases suspended sediment concentrations and turbidity in downstream water bodies; and fecal matter that may be washed into surface waters during rainstorms or snowmelt periods. The fecal matter also may contain pathogenic bacteria such as Escherichia coli (E. coli) that can pose a health threat to humans. This study aims to establish a working methodology to document and assess effects from backpackers and stock use on physical, chemical and biological water quality parameters. In July 2010, monitoring stations were established within the high-use Crabtree Ranger Station zone. Sites were selected to represent high backpacker use, high pack-animal use, and background conditions. Monitoring stations are instrumented to continuously record water level, temperature, and turbidity and to automatically collect storm samples. Water samples are analyzed for dissolved and particulate nutrients, suspended sediment, and E. coli concentrations. Preliminary data show E. coli counts averaged 4.5 Colony Forming Units/100ml (CFUs) at the high backpacker use, 29.0 CFUs at the high-pack animal use, and 3.4 CFUs at the background sites. Results from the nutrients and suspended sediment analyses are pending. Data collection continued throughout the 2011 field season, with the objective of better quantifying differences in water quality among the study sites.