Groundwater is under increasing pressure for water supply and irrigation. The water tables of principal aquifers in nearly the entire United States and in every European Union state are declining. Diffuse sources of pollution and underground disposal of wastes into the subsurface present competition to the resource as a sink for waste disposal. Use of deep ancient saline waters, injection of water to fracture rock for release of natural gas, and climate change reducing precipitation for recharge all present concerns for groundwater quality and use and provide opportunities to apply the field of economics to illuminate key considerations in groundwater project development. Different economic analytical approaches will be highlighted to reinforce the importance of developing and sharing this information for decision-making at both micro and macro levels. Implications for project development will be stressed, including usage, projections, and public perception.