A 7118 ft (2170 m) deep geothermal test well was drilled on the south edge of the city of Alamosa, Colorado as part of the Department of Energy's User Coupled Confirmation Drilling Program. The project was selected on the bases of a potential direct heat geothermal resource within the Rio Grande rift graben and resource users in Alamosa. The well site was selected on the hypothesis of a buried horst along which deep thermal fluids might be rising. In addition, there were city wells that were anomalous in temperature and the location was convenient to potential application. The Alamosa No. 1 penetrated 2000 ft (610 m) of fine clastic rocks over 4000 ft (1219 m) of volcaniclastic rock resting on precambrian crystalline rock at a depth of 6370 ft (1942 m). Due to poor hole conditions, geophysical logs were not run. The stabilized bottom hole temperature was 223/sup 0/F (106/sup 0/C) with a gradient of 2.6/sup 0/F/100 ft (47/sup 0/C/km). Limited testing indicated a very low production capacity. 16 refs., 6 figs.