Data from public and private sources on the Klamath Basin geothermal resource are reviewed, synthesized, and reinterpreted. In this, the second and final phase of the work, geological, remote sensing, geochemical, temperature gradient, gravity, aeromagnetic, and electrical resistivity data sets are examined. These data were derived from surveys concentrated on the east and west shores of Upper Klamath Lake. The geological, remote sensing, and potential field data suggest a few northeast-trending discontinuities, which cross the regional north-westerly strike. The near-surface distribution of warm water appears to be related to the intersections of these lineaments and northwest-trending faults. The groundwater geochemical data are reviewed and the various reservoir temperature estimates compared. Particular attention is given to specific electrical conductivities of waters as an interpretational aid to the subsurface resistivity results. A clear trend emerges in the Klamath Falls/Olene Gap area; hotter waters are associated with higher specific conductivities. In the Nuss Lake/Stukel Mountain area the opposite trend prevails, although the relationship is somewhat equivocal.

A synthesis and preliminary interpretation of predominantly geophysical information relating to the Klamath Basin geothermal resource is presented. The Swan Lake Valley area, northeast of Klamath Falls, and the Klamath Hills area, south of Klamath Falls, are discussed in detail. Available geophysical data, including gravity, magnetic, electrical resistivity, microseismic, roving dipole resistivity, audio-magnetotelluric (AMT) and magnetotelluric (MT) data sets, are examined and reinterpreted for these areas. One- and two-dimensional modeling techniques are applied, and general agreement among overlapping data sets is achieved. The MT method appears well suited to this type of exploration, although interpretation is difficult in the complex geology. Roving dipole and AMT are useful in reconnaissance, while gravity and magnetics help in defining structure. For the Swan Lake Valley the data suggest buried electrically conductive zones beneath Meadow Lake Valley and Swan Lake, connected by a conductive layer at 1 kilometer depth. In the Klamath Hills area, the data suggest a conductive zone centered near the northwestern tip of Stukel Mountain, associated with a concealed northeast-trending cross-fault. Another conductive zone appears near some producing hot wells at the southwestern edge of the Klamath Hills. These conductive zones may represent geothermal reservoirs. Specific types of follow-up work are recommended for each target area.