This study was performed on behalf of the Jefferson River Watershed Council and Trout Unlimited to define the ground water/surface water interaction in the Waterloo area of the Jefferson River. Three major irrigation ditches are located in this reach of the river, with two perennial spawning streams, Willow Springs and Parson’s Slough located in the north-central portion of the study area. Specific goals of the project were to define the nature of water movement through the study area and the interactions between the Jefferson River, Spawning tributaries, local irrigation ditches, mountain recharge, and ground water flow. The project was completed using a combination of historical data review, ground water characterization, surface, and stream flow monitoring and gauging. Surfacing water monitoring was conducted to assess stream and river flows conditions consisting of measuring stream flow conditions and velocities, and water quality. The field methods utilized to collect surface water data consisted of staff gauge readings, flow meters, and stilling wells equipped with Aquarods. Surface water levels were measured using permanent staff gauges at monitoring stations throughout the study area. Manual flows were measured using a March_McBirney Flo-Mate 2000 portable flow meter in accordance with standard USGS methods. Additional surface water locations were monitored periodically throughout the study area based on field inspections by WET personnel. A report was completed detailing the field data and methodologies utilized, ground water and surface water temperature/flow contour maps, data tables, with conclusions and recommendations to improve stream flows.