Bathing waters: Parasites and blue-green algae thrive in hot weather

Warm weather is creating ideal conditions for parasites and blue-green algae to thrive in bathing waters, posing potential risks to swimmers. An environmental officer, Maren Jarosch, was observed collecting water samples from Hamburg's Eichbaumsee, equipped with various tools for analysis.

Despite the lake appearing clear and blue from a distance, with ducks and ducklings swimming peacefully, the shore presented a different picture. A distinct blue-green sheen was visible along the water's edge, described as a color somewhere between a highlighter and toilet cleaner. Jarosch noted, "Something is hiding there," indicating the presence of potentially harmful substances.

This article, featured in the 32/2026 issue of ZEIT am Wochenende, delves into the implications of these findings. The presence of blue-green algae, also known as cyanobacteria, can lead to health issues if ingested or through skin contact. Parasites in the water can also cause infections and discomfort.

The report highlights the importance of monitoring bathing water quality, especially during periods of hot weather when such organisms proliferate. The collection of samples by environmental officers is a crucial step in assessing the safety of recreational waters and informing the public about potential hazards.

“

Something is hiding there.