Seismic noise measurements were made in the East Mesa area of Imperial Valley, California, to find out if a noise anomaly was associated with the Mesa thermal anomaly. Thirty-three locations were occupied in the area using slow-speed tape-recording seismic systems. One of the stations (CEN) was operated close to where a geothermal test well was subsequently drilled by the U. S. Bureau of Reclamation. Several sources of cultural noise are present in the area. Large fluctuations in noise level, superposed on a constant high level of noise, occur from traffic on a freeway to the south of the region. There is noise generated by canals to the west and south and agricultural activity to the west of the region. Noise at 2.5 Hz frequency generated by a small waterfall (power drop) on the All American Canal propagates as far as 10 km. Average noise levels were computed at each station using several quiet samples selected from 4-hour sections of data recorded at night and contoured. Spatial distribution of 2 to 3 Hz noise shows noise radiating from the power drop. Noise in 0 to 2, 3 to 5, and 5 to 10 Hz bands show high levels extending along themore » freeway to the south and East High Line Canal to the west of the area. The Mesa thermal anomaly is centered about 2.5 km from the freeway and canal and does not seem to have any anomalous noise amplitudes associated with it. Additional results using data from two arrays of closely-spaced instruments extending from the freeway to the Mesa thermal anomaly also show no indications of high noise levels over the anomaly. This conclusion differs from the results of two previous surveys in the area (Douze and Sorrells, 1972; Geothermal Staff of Teledyne-Geotech, 1972) which show well defined noise anomalies in the 0 to 2, and 3 to 5 Hz frequency bands. A search was also made for anomalous features in noise spectra and for coherent wave trains indicating the presence of discrete sources of noise.« less