The water quality of the Karlsfelder See is very good. This was the result of water samples recently taken by the Dachau health department: These were bacteriologically flawless. In addition, the Karlsfelder See was certified as having excellent bathing water quality in the current EU classification. The result is based on the test results of the past four years.
However, the health department had to repeatedly issue a bathing ban for Lake Ebertshausen last week. Blue-green algae with toxins in high concentrations had been detected there. The district office also advises against bathing in Lake Bergkirchen, even if no toxins have been found there so far.