The results of a first-stage evaluation of the overall feasibility of utilizing geothermal waters from the Madison aquifer in the vicinity of Poplar, Montana for space heating are reported. A preliminary assessment of the resource characteristics, a preliminary design and economic evaluation of a geothermal heating district and an analysis of environmental and institutional issues are included. Preliminary investigations were also made into possible additional uses of the geothermal resource, including ethanol production. The results of the resource analysis showed that the depth to the top of the Madison occurs at approximately 5,500 feet at Poplar, and the Madison Group is characterized by low average porosity (about 5 percent) and permeability (about 0.004 gal/day-ft), and by hot water production rates of a few tens of gallons per minute from intervals a few feet thick. The preliminary heating district system effort for the town of Poplar included design heat load estimates, a field development concept, and preliminary design of heat extraction and hot water distribution systems. The environmental analysis, based on current data, indicated that resource development is not expected to result in undue impacts. The institutional analysis concluded that a Tribal geothermal utility could be established, but no clear-cut procedure can be identified without a more comprehensive evaluation of legal and jurisdistional issues. The economic evaluation found that, if the current trend of rapidly increasing prices for fossil fuels continues, a geothermal heating district within Poplar could be a long-term, economically attractive alternative to current energy sources.