Officials found the toxin microcystin in the blue-green algae present at Discovery Bay, Calif. For people exposed to the toxin, symptoms include dizziness, rashes, fever, vomiting and in more unusual cases, numbness. Lesley McClurg/KQED hide caption

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Lesley McClurg/KQED

Poisonous Algae Blooms Threaten People, Ecosystems Across U.S.

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Soil erosion after five inches or more of rain fell in one hour across portions of Western Iowa in 2013. USDA Natural Resources Conservation hide caption

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USDA Natural Resources Conservation

Scientists with the U.S. Geological Survey sample water in Goodwater Creek, Mo., for pesticides and other chemicals that may have run off from the surrounding land. Abbie Fentress Swanson/Harvest Public Media hide caption

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Abbie Fentress Swanson/Harvest Public Media

What Is Farm Runoff Doing To The Water? Scientists Wade In

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