[The following pesticides were not detected in any samples: alachlor, atrazine, butylate, carbaryl, cyanazine, DCPA, EPTC, fonofos, malathion, methidathion, molinate, napropamide, pebulate, thiobencarb, and trifluralin. 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]