Two-dimensional, Backus-Gilbert inversion of the EMSLAB land magnetotelluric (MT) data along the 200--km-long Lincoln Line has yielded optimally smooth geoelectric sections. Inversions were performed on the apparent resistivity and impedance phase data approximating the transverse magnetic (TM) mode. The land portion of the Lincoln Line traverses the edge of the North American plate that is being underthrust by the Juan de Fuca plate system. The inversion reveals three centralized conductive zones in the depth range of 20--40 km. A slightly conducting (1000 ohm m) Western Cascades. Here the depth is too shallow for the zone to be the subducting plate. There is also evidence for a highly conducting (>1000 S) lower crust east of the High Cascades on the east end of the Lincoln Line. Two vertical conductive regions are also exposed in the inversion model. One occurs at 70--80 km from the coast under the Willamette Valley where a postulated Eocene trench may have left a suture zone. The second region is coincident with surface hydrothermal activity along the Western-High Cascades boundary. There are ample sources of water in the crust, e.g., in subducted sediments, from dehydration reactions along the upper plate boundary, and in volcanic arc magmas, to lead us to believe that hot, saline water is the magjor source of the conductive occurrences along the Lincoln Line. However, the various zones appear to be distinct, and the water may be trapped by different mechanisms. ¿ American Geophysical Union 1989