Microbial water quality and influences of fecal accumulation from a dog exercise area

The risk of water contamination by fecal bacteria may be increased if a watershed includes areas where feces accumulate as a result of specific land uses, such as areas where owners frequently exercise dogs. This study examined the effects of a year-round dog exercise area in the Burke Creek Recreational Area (BCRA) in the arid alpine environment of Stateline, Nevada. Burke Creek drains a small, high relief watershed, flows through a sedimentation basin in the BCRA, and enters Lake Tahoe. Over the course of 14 months, we analyzed water samples from the creek for Escherichia coli and collected feces from plots to estimate fecal accumulation. We found that accumulation was highly localized within the study area, amounting to approximately 100.1 lbs (45.5 kg) of dry matter in 14 months. Statistical analysis indicated, however, that fecal bacteria in water decreased as the stream flowed through the area, presumably due to effects of the sedimentation basin, wetlands, and die-off of E. coli in feces from exposure to environmental stresses. These results are useful for managing heavily used sites and understanding the effects of this type of land use on water quality.