(Beyond Pesticides, August 21, 2009) Pesticide use around our homes are an underestimated source of water pollution – leading to more than 50 percent more water pollution than previously believed, according to scientists looking at pesticide use in residential areas in California. The polluted runoff has been linked to fish kills and loss of aquatic species diversity. The findings of a new study were reported earlier this week at the 238th National Meeting of the American Chemical Society in Washington, DC.
In the study, Lorence Oki, from the Department of Environmental Horticulture at the University of California Davis, Darren Haver, with University of California Cooperative Extension, and their colleagues explain that runoff results from rainfall and watering of lawns and gardens, which winds up in municipal storm drains. The runoff washes fertilizers, pesticides and other contaminants into storm drains, and they eventually appear in rivers, lakes and other bodies of water.
“Results from our sampling and monitoring study revealed high detection frequencies of pollutants such as pesticides and pathogen indicators at all sites,” Mr. Oki said of their study of eight residential areas in Sacramento and Orange Counties in California.
Preliminary results of the study suggest that current models may underestimate the amount of pollution contributed by homes by up to 50 percent. That’s because past estimates focused on rain-based runoff during the wet season. “Use of pesticides, however, increases noticeably during the dry season due to gardening, and our data contains greater resolution than previous studies,” said Mr. Oki.
Organophosphate and pyrethroid pesticides were found in all water samples taken over a two year period on a weekly, bi-weekly and monthly basis for the study, according to Scientific American. The majority of the pesticides detected in the runoff were for ant control, which is supported by data from the California Department of Pesticide Regulation that has shown that the majority of pesticides purchased by homeowners are used to control ants.
Last month, the report “Pesticides and the Maryland Chesapeake Bay Watershed” was released, warning that pesticide pollution from households and farm fields is contributing to the Chesapeake Bay’s decline, and may well be linked to declines in frogs across the region and intersex fish seen in the Potomac River.
Another study reported by Beyond Pesticides last month found that insecticides used in highly populated agricultural areas of California’s Central Valley affect amphibians that breed in the Sierra Nevada Mountains to the east. This study adds to the increasing evidence that pesticides impact areas and wildlife species that are miles from sources of pesticide application.
To lessen your impact on water pollution, avoid using hazardous pesticides by choosing non- and least toxic pest management strategies and support organic agriculture. For more information on issues related to pesticides and water pollution, see Beyond Pesticides Threatened Waters program page and the Daily News Blog.