An aerial remote sensing study of Baltimore Harbor and the Wicomico River Basin was conducted on 9 May 1973. This investigation was undertaken at the request of the Department of Natural Resources, State of Maryland. The purpose of the Baltimore Harbor study was to document the presence of discharges of wastewater to the Harbor from municipal and industrial sources, storm drains, and other unidentifiable sources. Photographic and thermal infrared data were recorded during the day and thermal infrared data were recorded at night using sensors mounted in high performance reconnaissance aircraft. No ground truth was collected. All observed discharges were compared to known municipal and industrial wastewater discharges to identify locations of potential sources that had not filed for waste discharge permits. In addition, the relative magnitude, color, dispersion behavior and, in some cases, relative levels of concentrations of the detected discharges and resulting plumes were documented.