Only at the Schmöckwitz bathing area on the Dahme and at the small bathing meadow on the Unterhavel is there a warning about blue-green algae, which restricts visibility. You should avoid streaks there because blue-green algae toxins could be present in high concentrations. At Groß Glienicker See, there is also a warning about an increased bacterial count caused by the heavy rainfall in recent weeks. During heavy rainfall, untreated wastewater, among other things, can be washed into the water. According to the state office, this can lead to contamination at times. Before visiting a body of water, day trippers can find out about potential warnings on the state office's website.