[Sites 3, 4, 5, 7, 8, 11, 12, 13, 16, 17, 18, 20, 23, 24, 27, and 31 were not sampled during the period. The following pesticides were not detected in any samples: alachlor, atrazine, butylate, carbofuran, cyanazine, DCPA, diazinon, fonofos, malathion, methidathion, napropamide, pebulate, and thiobencarb. Concentrations are shown in nanograms per liter. Numbers in brackets are USGS National Water Information System (NWIS) parameter codes. hh, hours; id, identification; mm, minutes; mm/dd/yyyy, month/day/year; nd, not detected, ( ), detected at a concentration less than the method detection limit]