Passage III

A pesticide applied one time to orchards located near Site 1 (see Figure 1) a t the end of January was detected shortly afterward in the waters of an adjacent river system and bay. Figure 2 shows the data collected daily in February at Site 1: the pesticide concentration in the river water, in nanograms per liter (ng/L); the inches of rain that fell in the area during several storms; and the river dis­charge (in ft³/ sec). Discharge is the volume of water passing a given point in a given amount of time. Figure 3 shows pesticide concentrations for February 4 through February 25 at the 3 sites shown in Figure 1.

Figures adapted from Kathryn Kuivila, "Diazinon Concentrations in the Sacramento and San Joaquin Rivers and San Francisco Bay, California, January 1993." ©1993 by the U.S. Geological Survey.