HIGH DIAZINON CONCENTRATIONS IN THE SAN JOAQUIN RIVER WERE COMMON FOLLOWING WINTER APPLICATION

Diazinon concentrations in the San Joaquin River near Vernalis, California, exceeded concentrations shown to be toxic to aquatic life during January and February 1993--following the winter application of diazinon, a dormant spray applied to control wood-boring insects in almond orchards in the San Joaquin-Tulare Basins.