The first U.S. DOE Laramie Energy Technology Center (LETC) steam flood experiment in a Utah tar sand, LETC TS-IS, was conducted in the Northwest Asphalt Ridge deposit near Vernal, UT> Steam was injected into the center well of two concentric invented five-spot patterns. The zone chosen for the experiment was a sand stone 45 ft (14m) thick in the Rimrock member of the Mesa verde formation. The pattern area was 0.25 acres (1012 m2) and contained a 13 degree API (979 kg.m3) bitumen with a viscosity greater than 10^6 cp (10^3 Pa*s) at reservoir conditions. The average oil saturation was 78.9% PV. During 160 days of operation, 65,700 bbl (10.4 x 10^3 m3) of water-equivalent steam were injected at 360 to 530 psig (2.5 to 3.7 MPa) and 180 to 650 B/D (29 to 103 m^3/d). Total production during the test amounted to 1,150 bbl (183 m3) of oil and 6,250 bbl (994 m3) of water.