Human

• Large catchment area above dam: To provide a reliable water supply
• Total cost of dam construction: Influence whether the project is economically viable
• Proximity of labour (accommodation/food etc): If closer makes the build cheaper overall
• Close to construction materials: Reduces the cost of transporting the materials to the construction site
• Political influence: More kudos for politicians if its built within their 'patch'
• Proximity of urban/agricultural areas (for water and electricity supply): Will determine whether transport costs outweigh the price of the water and electricity. Longer distance = more evaporation if water is in a canal
• Proximity to historical sites/native cultures (e.g. Colorado - native American burial sites): Avoid offending these cultures by destroying significant sites
• Cost of displacing people/ compensating farmers/ homeowners: Determines whether the economic gains of the dam will outweigh the costs