Evaluation of the Water Quality Significance of OP Pesticide Toxicity in Tributaries of Upper Newport Bay, Orange County, CA

摘要

Stormwater runoff in San Diego Creek, the primary tributary to Upper Newport Bay in Orange County, CA, has been found to be toxic to Ceriodaphnia and Mysidopsis with total acute 24 hr toxicities up to 16 acute toxic units (TUa). About half of this toxicity has been found to be due to the organophosophate (OP) pesticides diazinon and chlorpyrifos used in urban areas for structural termite and ant control, and lawn and garden pest control. The other half is due to unknown causes likely associated with the use of pesticidesin commercial nurseries and agriculture. The non-stormwater flow into Upper Newport Bay is non-toxic. Stormwater runoff events cause short-term pulses of toxic waters to enter this marine bay.