Protection of headwater catchments from future degradation: San Miguel River Basin, Colorado

A study of high-elevation catchments in the San Miguel River Basin of south west Colorado was conducted during the summer of 1997 to develop a scientif ically based tool for water resources management. The authors mapped landsc ape types and associated water quality parameters with those types, enablin g sensitivity assessment at the landscape unit scale, thus addressing catch ment heterogeneity. Landscape-type maps and derived sensitivity maps were e ntered into a geographic information system (GIS). They proved effective vi sual tools for use in policy decisions and public presentations. Water qual ity issues addressed were sensitivity to acidification and nutrient enrichm ent. Landscape types associated with surface waters having growing season a cid neutralizing capacity (ANC) < 50 <mu>eq/L were considered sensitive to acidification and included talus and mining-related areas. Types sensitive to nutrient enrichment were those having average growing season NO3- concen trations > 9.0 mu eq/L, and included tundra, talus, and rock glaciers. Usin g the results of this study, San Miguel County commissioners adopted regula tions for restricting development in sensitive high-elevation areas, includ ing limits on building footprints and bans an septic systems. The adoption of these regulations lays the foundation for future application of this app roach to headwater catchments in other western US locations.