Heavy rain releases sewage into Charles River and Mystic River

Public health officials say people should avoid activity in parts of two Massachusetts waterways for 48 hours after Tuesday's storms, when extensive rain caused sewage to be discharged

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Public health alerts have been issued for parts of Massachusetts' Mystic River and Charles River because of Tuesday's very wet weather.

Sewage was discharged into the waterways during the downpours. The release is common during heavy rains to keep contaminated water from getting into homes, businesses and streets, but it does make the rivers' water unhealthy.



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"In one hour, we got enough rain — that pretty much only happens once every 25 years at that intensity — and so our systems aren't designed to handle that water and sewage at the same time," said Patrick Herron, executive director of the Mystic River Watershed Association.

For more than two hours, a combination of rain and contaminated effluence was discharged directly into the Mystic River. It happened along the Charles near Magazine Beach in Cambridge, as well.

The Massachusetts Water Resources Authority lists 11 locations on a CSO discharge table.

Map from the Massachusetts Water Resources Authority as of 7:30 p.m. The purple squares represent treated discharge in the last two days, the brown circles represent untreated discharge in the last two days, and the green circle shows no recent untreated discharge.

The release of combined sewage outflows, or CSOs, is done in older systems, allowing bacteria and other pollutants into the water. People are urge to avoid contact for 48 hours.

"It can make it unsafe to recreate. If you got that in your mouth, you'd have gastrointestinal issues. On the long-term, it's contributing a lot of nutrients and suspended solids that can decreases the health of waterways," Herron said.

The water is clearing up, but people should limit activities on both rivers until Friday if possible.

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