Using a semiquantitative analytic hierarchy process (AHP), watershed vulnerability was assessed for Bernalillo County, New Mexico, an area that is characterized by intermittent precipitation events and limited water availability. The model was designed using a multicriteria decision support (MCDS) methodology implemented in a geographic information system (GIS). A vulnerability map was produced by means of a weighted overlay analysis that combined soil erosion and infiltration maps derived from the AHP. Model results were categorized into five vulnerability classes: not vulnerable (N), slightly vulnerable (SV), moderately vulnerable (MV), highly vulnerable (HV), and extremely vulnerable (EV). The results indicate that approximately 83% of the study area is SV to MV, and less than 4% of the area is HV or EV. Shrub land-use classes were identified to experience the most vulnerability. Model output compared similarly with the results predicted by the revised universal soil loss equation (RUSLE) model with the exception of the N class. The eastern portion of the county was identified as most vulnerable because of its high slope and high precipitation. In this large area scenario, structural stormwater control measures (SCMs) may be viable for managing runoff and sediment transport offsite. This MCDS/GIS approach can provide useful information to guide local governments and decision makers in selection of suitable structural and nonstructural SCMs for the arid Southwest.