A time domain electromagnetic sounding survey of the region surrounding the city of Los Alamos, New Mexico was carried out. The results show that a linear trough, trending northeast--southwest runs beneath the city. The southern boundary is somewhat to the south of the city, the northern boundary was not established. The geoelectric section consists of three layers and the total thickness of the section is in excess of 3 000 m. The resistivities of the second layer are as low as 2.5 ..cap omega.. m. If the salinities are in the region of 7 000 ppm, the resistivities could indicate that water with a temperature of 150/sup 0/C may be found at a depth of 3 000 m.