Overview
- Health offices have issued swim warnings or bans at sites including Warnemünde, Seeburger See, a small Lindau pond, Altmühlsee and the Uettelsheimer See where a water play area was closed.
- Cyanobacteria, often called 'blue‑algae' though they are bacteria, thrive in warm, calm water and can form green‑blue surface scums that sometimes contain toxins.
- Exposure can cause skin irritation, eye redness, nausea, vomiting, diarrhea, fever or breathing problems and can be deadly for dogs that drink the water, so authorities warn people and pet owners to stay away.
- Officials say routine monitoring and lab tests guide warnings and bans, that serious human cases in Germany have been rare, and that those with minor contact should shower and wash swimwear and seek medical help for symptoms.
- Experts warn warming summers make blooms more likely in future summers, but the exact scale and timing of any increase remain uncertain and will depend on local weather and water conditions.