Czech Republic water quality monitoring shows mixed swimming safety

Regional health officials in the Ústí nad Labem area reported that most natural swimming sites have clean water, with green algae observed in some ponds but still safe for bathing. Popular locations such as Kamencové jezero in Chomutov, the Labe River in Ústí nad Labem and municipal pools attracted many visitors.

Nationwide monitoring released on 7 July 2026 shows that while the majority of Czech natural bathing sites remain suitable, several locations are flagged for elevated cyanobacteria levels, prompting swimming bans at Kachlička, Sedlice, Orlík (Podolsko) and Stříbrný rybník. Other sites—including Velký rybník (Karlovarský kraj), Máchovo jezero, Hamerské jezero, Trutnov Dolce, Oborský rybník and Tvrdkov—show deteriorated water quality but bathing is still allowed with precautionary showering, especially for children, pregnant women, allergy sufferers and immunocompromised persons. Authorities advise the public to follow updates on the official portal.