The increase in highways, parking lots, and driveways between 1938 and 1991 would lead to increased runoff of road salt, oil, and other contaminants. Conversion of farm fields to residential and commercial uses could have caused either an increase or a decrease in runoff of fertilizers and pesticides, depending on the intensity of management of the farm land and of the lawns, golf courses, and parks that replaced it. Sources of Aerial Photographs Historic and current aerial photographs are readily available from a variety of sources including local, state, and federal governments as well as private firms. Local sources include planning offices, highway departments, assessment offices, health departments, and soil and water conservation districts. State departments of transportation usually have aerial photographic coverage of strips along state and federal highway systems and of some urban areas.
Some states have coverage for the entire state.
For More Information Barnaba, E.M., W.R. Philipson, A.W. Ingram, and J. Pim. 1991. The use of aerial photographs in county inventories of waste-disposal sites. Lillesand, T.M., and R.W. Kiefer. Remote Sensing and Image Interpretation , 2nd ed. Avery, T.E. and G.L. Berlin.