Do fish ponds cause Legionnaires’ disease?

We have been notified that a fish pond with Japanese carp will have to be cleared due to the health risk of Legionnaires’ disease. Is it not possible to eliminate the risk in such a confined public area? If the pond has to be cleared, wouldn’t all outside ponds need to be cleared?


Although Legionella may be found in extremely low numbers in natural aquatic bodies of water (like a pond), there is little opportunity for amplification (growth) and transmission. We are not aware of any reported cases of Legionnaires’ disease associated with natural ponds. So, we see little risk of contracting Legionnaires’ disease and would not be concerned. No guidelines for ponds, including fish ponds, have been formulated with respect to Legionnaires’ disease. On the other hand, rare cases of Legionnaires’ disease have been linked to natural hot springs.