The Suffolk County Health Department warned residents Wednesday to continue avoiding contact with waters in the tidal area of the Peconic River east of Grangebel Park, as an upgrade to the Riverhead sewage treatment plant continues.

Earlier warnings indicated high rates of chlorination at the plant, which led to “a visible plume of cloudy water” as well as the potential impact of “inadequately treated wastewater” being discharged.

Both those situations have improved, health officials said, but a recent water sample showed elevated levels of coliform bacteria. That and the potential for further issues “as the plant proceeds with upgrades” mean it’s best to avoid water contact until the upgrade job is done, with a major part of the work estimated to be completed by February.

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Children and pets also should be kept away from the area, but if contact with water is made, rinse off immediately, officials said.

If symptoms occur, including “nausea, vomiting or diarrhea; skin, eye or throat irritation; or allergic reactions or breathing difficulties,” health officials said to seek medical help.