Water quality & forest road management in the Lake Tahoe Basin

Lake Tahoe, located high in the Sierra Nevada mountains of California and Nevada, is widely recognized as a national treasure and has been congressionally designated as an "Outstanding National Resource Water." Currently, the Lake's famed clarity is decreasing by an average of 1.5 feet per year. In 1998, the USDA Forest Service, Lake Tahoe Basin Management Unit began addressing water quality impacts associated with Forest Service roads in the Lake Tahoe Basin. Unsurfaced roads have been identified as a source of nutrients (primarily phosphorus) which impact lake clarity by increasing primary productivity through erosional processes and atmospheric deposition by fugitive dust. As a first step, an Access and Travel Management Plan (ATM) was initiated. This included the development of a risk assessment quantifying each road's potential to adversely impact water quality. This provides an unbiased analysis process allowing the Forest Service to consider road need versus risk when making decisions to upgrade or decommission roads. It is also a useful tool for prioritizing road treatments given constrained budgets. Another component was the development of an interactive GIS database. This system provides an effective mechanism to store and analyze the large amounts of spatial and tabular information gathered during ATM development.