[en] An aerial radiological survey was conducted over the Quad Cities Nuclear Power Station in Cordova, Illinois, during the period May 9 through May 18, 1989. The survey was conducted at an altitude of 61 meters (200 feet) over a 65-square-kilometer (25-square-mile) area centered on the power station. The purpose of the survey was to document the terrestrial gamma environment of the Quad Cities Power Station and surrounding area and to determine any radiological impact on the area over the past twenty years. The results of the aerial survey are reported as inferred gamma radiation exposure rates at 1 meter above ground level in the form of a contour map. Outside the plant boundary, exposure rates were found to vary between 5 and 15 microroentgens per hour (μR/h) and were attributed to naturally-occurring uranium, thorium, and radioactive potassium gamma emitters. The aerial data were compared to ground-based ''benchmark'' exposure rate measurements and radionuclide assay of soil samples obtained within the survey boundary. The ground-based measurements were found to be in good agreement with those inferred from the aerial measuring system