| coliform bacteria in sierra nevada wilderness lakes and streams: what is the impact of backpackers, pack animals, and cattle? | the presence of coliform bacteria indicates a watershed risk for harboring microbes capable of causing human disease. we hypothesized that water from watersheds that have different human- or animal-use patterns would have differing risks for the presence of coliform bacteria. methods; water was collected in wilderness areas of the sierra nevada range in california. a total of 60 sites from lakes or streams were selected to statistically differentiate the risk categories: 1) high use by backpacke ... | 2006 | 16538940 |