The potential effect of underground coal gasification(UCG) on groundwater has been examined in a combined field and laboratory study. The study was directed at Fruitland Formation subbituminous coal of the San Juan Basin and at the groundwater found in this coal seam. A field site for a possible UCG test was selected and two wells were drilled into the coal seam which lies about 500 ft. below the surface. Groundwater samples were collected and used to establish baseline features. Core samples of overburden, underburden and coal were used for baseline characterization of the minerals.