Environment America Reports Widespread Bacteria in Waterways

A new study reveals that over two-thirds of tested U.S. river and lake sites show potentially unsafe bacteria levels.

Updated on Oct. 30, 2026 in Current Conditions

Bold flat-color editorial illustration depicting a glass sampling vessel and ripples, representing systemic water quality research. — Environment America reported that 69 percent of 4,500 tested U.S. waterway sites showed potentially unsafe bacteria levels including widespread E. coli. AI Illustration. Upload story photo >

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Do you research water quality advisories before swimming in local lakes or rivers?

Environment America found unsafe bacteria levels at 69 percent of 4,500 tested water locations across 17 states. E. coli was identified in every state included in the analysis.

Why it matters

Contamination in these popular waterways often stems from sewage overflows, stormwater runoff, and leaking septic tanks. Half of the monitored sites recorded elevated E. coli levels on at least 25 percent of test days.

Researchers identified potentially unsafe bacteria levels at 69 percent of 4,500 river and lake locations across 17 states. Elevated E. coli levels were recorded at approximately 50 percent of sites on at least 25 percent of test days.

The players

Environment America

This is a national federation of environmental advocacy groups focused on clean water, clean air, and climate action policies.

The details

Testing revealed that E. coli is present in every state analyzed within the report. Contamination is frequently driven by sewage overflows, stormwater runoff, and failing or leaking septic systems.

Environment America published the Safe for Swimming report on October 30, 2026.

Seasonal Patterns

This data adds to the ongoing tracking efforts monitored by the Environmental Protection Agency's water quality portal. These findings demonstrate that water safety concerns persist across diverse regions regardless of established federal oversight.

To reduce exposure risk, the public should avoid swimming in lakes and rivers for 48 to 72 hours following heavy rain events. Residents can verify local safety by checking official county health advisories or the EPA water quality portal.

The takeaway

Swimmers should remain vigilant by checking local health alerts before entering natural water bodies. Avoiding recreational water contact after rainfall remains the most effective way to minimize the risk of bacterial infection.