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Pyrethroids in Creeks by Dave Tamayo, Way back at the end of the last century (the 1990s), the Sacramento Stormwater Quality Partnership (or SSQP, which includes Sacramento County and the cities of Citrus Heights, Elk Grove, Folsom, Galt, Rancho Cordova, and Sacramento) found that the water in local creeks was contaminated with the insecticides diazinon and chlorpyrifos, at levels toxic to the water flea Ceriodaphnia. Since then, most urban uses of these chemicals have been phased out, only to be largely replaced in the urban marketplace with pyrethroids. In our area, pyrethroids are widely used for ant control around buildings, in most aerosol bug sprays, and even in combination with lawn fertilizers (even though the target insects rarely cause problems in Sacramento lawns). Recent studies by Professor Donald Weston of U.C. Berkeley frequently found pyrethroids at toxic levels in urban creek sediments of the Sacramento region and the Bay Area. Weston's studies also indicate that urban areas, not upstream agriculture, are the source of these chemicals in the creeks. Pyrethroids bind strongly to sediments, so that the vast majority of them will be found in the stream bottom. This is better for animals like Ceriodaphnia that swim and don't interact much directly with the sediment. However, animals that dwell on or in the stream bottom are at risk, since they are more likely to contact the pyrethroids. Weston's study animal, Hyallela azteca, is a sediment-dwelling amphipod crustacean found naturally in this area, and is an important component of the aquatic food web. To help prevent harm to creek life, SSQP actively encourages residents and professionals to reduce pesticide use wherever possible. In addition, the SSQP is a leader in the effort to prod State and Federal pesticide regulators to re-evaluate pyrethroids, and to improve the overall process for pesticide regulation. A key goal is to evaluate pesticides more effectively so future water quality problems are avoided before pesticides are allowed on the market. Visit the Sacramento Storm Water Quality Partnership for resources on avoiding pesticide use. Our Water Our World and WaterWise are two programs supported by the Sacramento Stormwater Partnership that provide useful information for managing pests in Sacramento area landscapes. These programs distribute information through retail outlets and the internet. Water Wise also provides help through the Sacramento Master Gardeners who can answer specific questions during business hours at (916) 875-6913. Our Water Our World provides individual assistance on pest management issues through Ask the Expert, which links to the Bio-Integral Resource Center (www.birc.org). The University of California Statewide Integrated Pest Management Program has abundant information on IPM for landscapes, especially in its Pest Notes, and Turf sections.
Sacramento Urban Creeks Council |
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