WASHINGTON — The amount of water pollution contributed by homes may have been underestimated by up to 50 percent, according to researchers who presented their findings during the 238th National Meeting of the American Chemical Society (ACS), being held here through August 20.

According to an ACS August 19 press release, the study of eight residential areas in California’s Sacramento and Orange counties found that runoff from rainfall and lawn-watering ends up in municipal storm drains. It washes fertilizers, pesticides and other contaminants into storm drains, and they end up 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,” researcher Lorence Oki said of the study. Darren Haver and colleagues joined Oki in the study.

Researchers said prior models for estimating residential runoff 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,” Oki said.

Pollutants detected in outdoor runoff included ant-control pesticides. Previous surveys have shown that the majority of pesticides purchased by homeowners are used to control ants. To encourage pollutant reduction, the researchers started community outreach programs centered on improving both irrigation control and pest management, the release said.

To read the full release, click here.

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