"It is estimated that the United States contains approximately 30-billion barrels of tar sand resource (1) . Of this total, approximately 28-billion barrels is found in Utah. The technology necessary to extract the bitumen from the sandstone is still being developed. Active research is required to determine the most appropriate extraction technologies. The research program of the U. S. Department of Energy's (DOE) Laramie Energy Technology Center (LETC) has been concerned with investigating in situ technologies to develop that portion of the resource unavailable for either technical or economic reasons, for extraction by conventional mining methods. To date, many laboratory and three field experiments have been conducted. The results from these experiments have been previously reported (1, 2,3,4,5). Field efforts have been conducted in the Northwest Asphalt Ridge Deposit near Vernal, Utah. The first two experiments were attempted in 1975 and 1977, and employed combustion technologies. The third field experiment was conducted during 1980 and evaluated the feasibility of employing a steam drive technique to extract the bitumen from the formation. A once-through steam generator using relatively pure water was employed. A total of 65,700 barrels (10.4 dams3) of water equivalent steam were injected into the formation during the 160 days of testing. Oil production for this experiment equaled 1,150 barrels (183 m3), with recovered water being 6,250 barrels (994 m3)(6). This paper reports results from laboratory scale research which investigated treatment options and configurations necessary to recycle these waters back to a steam generator."