An attempt was made to determine the physical and economic impacts of the water resources development on the seven major uses: (1) irrigation, (2) recreation, (3) power, (4) municipal and industrial use, (5) flood control, (6) water quality and (7) fish and wildlife. The study area was the Mountain Home Division of the Southwest Idaho Water Development Project. The major effort of the investigation was centered around the two functions, irrigation and recreation. Economic models were developed for these two functions. In measuring the changed conditions from new irrigation land development two approaches were used. One was simple budgeting analysis and the other was using a Linear Programming model including sensitivity analysis. Parametric programming on the objective function was used for two of the activities, sugar beets and potatoes. The recreation model was limited to the empirical investigation of pheasant hunting in the Southwestern Idaho region. The over five functions of multiple water uses are treated in a descriptive manner.