Aerial photographs of several Tennessee Valley Authority (TVA) reservoirs are taken each year to determine acreages of the dominant species of submersed aquatic macrophytes. This paper describes methods used in obtaining and interpreting the photographs. For operational work, the TVA uses large-scale color photographic prints made from a color-negative film. Although more expensive than black-and-white (BW) film, the color film allows better discrimination of submersed species of aquatic plants. While false-color (color-infrared) film has been widely used for mapping and monitoring emergent and wetland plant communities, it is less desirable than true-color film for delineating and mapping submersed plants. Scales of 1:7 200 and 1:12 000 are commonly used and provide the detail and resolution needed for accurate photointerpretation of several submersed macrophyte species.

The TVA is also experimenting with an airborne thermal line scanner for mapping aquatic plants. The imagery from the system can in some cases be used to delineate the limits of colonies of Eurasian water milfoil according to differences in surface water temperatures.