The goal of this thesis was to implement a GIS tool to help identify potential locations for hydroelectric power projects in Patagonia, Chile that are in accordance with environmental and social impact assessments. I first identified river basins with high hydropower potential and then assigned weighted values to those basins, in order to minimize the displacement of indigenous populations, damage to archaeological and historical sites, and identify regions with the lowest threat to biodiversity. I used the weighted overlay tool as a decision support system to balance the competing environmental and social interests in relation to hydroelectric development in Patagonia. The results identified 5 sites that are the highest scores among all factors. This work indicates that GIS data and decision support systems can help provide useful information for the decision makers.