Lake Balaton algae concentrations stay below safety threshold

The Balaton Limnological Research Institute reported that, while algal biomass in Lake Balaton has risen in recent weeks, the chlorophyll‑a concentration remains below the World Health Organization's 75 µg/L health limit across the entire lake. The highest readings, 50‑52 µg/L, were recorded in the western basin on July 28, whereas eastern waters showed lower values of 26‑30 µg/L.

Cyanobacterial filamentous species have become more prevalent throughout the lake, but their abundance is still insufficient to pose a health risk. Dominant genera include Aphanizomenon, Planktothrix, and Cuspidothrix, with a growing presence of Raphidiopsis. The planktonic diatoms Ceratium hirundinella and Ceratium furcoides are also increasing toward the western end.

A temporary swimming ban was imposed at the Helikon beach in Keszthely due to elevated bacterial counts (E. coli 1,382 MPN/100 ml; Enterococcus 720 MPN/100 ml). Authorities will reassess water quality before reopening, while other western‑lake beaches continue to meet quality standards. Ongoing monitoring is planned to track the lake’s condition.