Czech natural swimming sites show mixed water quality, some with cyanobacteria alerts

In the Liberec region, hygiene officials said three natural swimming ponds have slightly reduced water clarity, raising a small health risk. They recommend swimmers shower after use. Water quality has improved at Máchovo Lake, while the Mšeno dam and the flooded Kristýna pit are rated clean. The Vápenka pool in Liberec is expected to remain closed for the summer.

In the Karlovy Vary (Cheb) region, most natural bathing places rank at quality level 1‑2 and are suitable for swimming. However, the Skalka reservoir was measured at level 3, showing cyanobacteria and prompting health warnings. Other sites such as Lido in Mariánské Lázně received a level‑1 rating, and several reservoirs were recorded at level‑2.