Pesticide Concentrations Measured During In-Situ Active Water Sampler Testing in Solano County, California, 2023

A novel U.S. Geological Survey-developed active water sampler was deployed at Ulatis Creek in Solano County, California for 24 hours from November 15, 2023 to November 16, 2023. Discrete surface water samples were collected at the start and end points of the active water sampler deployment interval for comparison to the active water sampler. Samples from the active water sampler and the discrete surface water samples were analyzed for 183 pesticides dissolved in water and 178 pesticides in suspended sediment at the U.S. Geological Survey Organic Chemistry Research Laboratory in Sacramento, California. Twenty-seven out of 183 pesticide compounds measured in sample extracts were detected in at least one of the grab sample or active sampler dissolved water extracts with concentrations ranging from 0.9 nanograms per liter to 32.2 nanograms per liter. No pesticides were detected in the suspended sediment filtered from the water.