This study was designed to provide a physical and ecological analysis of paired watersheds in the semi-arid western juniper (Juniperus occidentalis) woodlands of Central Oregon. Instrumentation and monitoring was accomplished in Jensen and Mays watersheds as the preliminary portion of a longer term project. Instrumentation was designed to address changes in the erosional processes, hydrology, and vegetation on a watershed scale. Instrumentation was setup to assist in the comparison and calibration of water flow out of the watersheds. This information will be used in the long-term study in conjunction with the treatment of the western juniper overstory on one of the watersheds. Determination of the study area in each watershed required extensive reconnaissance with the assistance of aerial photos, topographic maps, and Geographic Information Systems (GIS). Mapping of the study areas was accomplished with GIS and Global Positioning Systems (GPS). Watersheds were paired according to specific characteristics that influence treatment effects. Flume types were chosen with respect to precipitation intensity and frequency with placement being more a function of watershed topography and channel morphology. Upland sedimentation and erosion measurement required intense acknowledgement of both abiotic as well as biotic characteristics. Analysis showed the watersheds to be similar in size, percent juniper, grass and bare soil cover, topography, and precipitation frequency and intensity. Differences were obtained relative to erosional processes, area of different soil types and channel discharge. Further monitoring and calibration should provide greater insight into the comparison of these components of the study. / Graduation date: 1996