The subbituminous coal of the San Juan Basin of northwestern New Mexico is one of the largest and most accessible coal deposits of the Southwest. The total amount of subbituminous coal in the basin has been estimated to be about 5,000 quads of which 250 quads lie within the limits of strip mining, that is, within 250 feet of the surface. The remainder, some 4,750 quads, are the deep deposits which well probably only be tapped by some version of the technique of underground coal conversion. The most nearly viable underground conversion method at the present time is underground coal gasification which has been explored in a number of countries, notably Russia and England, for a number of years, and has been tested in this country at Hanna, Wyoming. The basic technology is available at this time, through a number of difficult engineering problems remain. There also remains one very serious technical question, the answer to which is likely to determine whether this potential energy source is converted or not: what is the environmental impact?