Effects Of Ddt Spray On Fish And Aquatic Insects In Gallatin River Drainage In Montana

DDT was sprayed at 0.5 pound per acre for elm spanworm control in two drainages in north Georgia in both 1959 and 1960. In one drainage, precautions were taken to avoid the stream, and no significant mortality to aquatic organisms resulted. In the other drainage, DDT reached the stream in a normal spray operation, and serious depletion of aquatic invertebrates resulted. Recovery of bottom organisms was rapid, and total numbers of invertebrates were up to pre-treatment levels after four months.