Occurrence of pesticides in water, sediment, and soil from the Yolo Bypass, California

San Francisco Estuary and Watershed Science
By: , and 



The objective of this study was to evaluate the potential sources of pesticides to the Yolo Bypass, including those that could potentially impact critical life stages of resident fish. To assess direct inputs during inundation, pesticide concentrations were analyzed in water and suspended and bed sediment samples collected from source watersheds during high-flow events. To understand inputs from direct application on fields, pesticides were also measured in soils collected from several sites within the Bypass. Thirteen current-use pesticides were detected in water samples collected in 2004 with the highest pesticide concentrations observed at the input sites to the Bypass during high-flow. Hexazinone and simazine were detected at all sites and at some of the highest concentrations. In bed and suspended sediments collected in 2004 and 2005, thirteen current-use pesticides were detected along with DDT and its metabolites. Trifluralin, DDE, and DDT were highest in the bed sediments, whereas oxyfluorfen and thiobencarb were highest in the suspended sediments. With the exception of the three organochlorine insecticides, suspended sediments had higher pesticide concentrations compared to bed sediments, indicating the potential for pesticide transport especially during high-flow events. Soil samples were dominated by DDT and its degradates but also contained a variety of current-use pesticides typically at lower concentrations. The types of pesticides detected in water and sediments were correlated with agricultural application in each watershed.

Understanding the distribution of pesticides between the water and sediment is important in assessing their fate and transport within the Bypass, and in evaluating the exposure and potential effects to resident fish.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Occurrence of pesticides in water, sediment, and soil from the Yolo Bypass, California
Series title San Francisco Estuary and Watershed Science
DOI 10.15447/sfews.2007v5iss1art2
Volume 5
Issue 1
Year Published 2007
Language English
Publisher eScholarship University of California
Contributing office(s) California Water Science Center, Toxic Substances Hydrology Program
Description 17 p.
Country United States
State California
Other Geospatial Yolo Bypass
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details