Algae plague in Aachen Weiher: City fights for clear water!

Algae plague in Aachen Weiher: City fights for clear water!

The algae plague at Aachener Weiher in Cologne presents the city with a challenge. Especially during the hot days, a worrying trend has been shown: thick algae carpets spread over the water surface, which extend to the surface. This situation is not only to be seen disturbing, but also in the frugal areas. The water of the pond has no drinking water quality anyway, which makes the matter even more explosive. According to the Express , the algae fields from the Hiroshima-Nagasaki-Park are clearly visible and arouse concern for walks and residents.

The Cologne city drainage companies (Steb) are responsible for the water quality of the pond. They had recently struggled with a defective mowing boat that is used to combat algae population. Spokeswoman Birgit Konopatzki announced that the mowing boat will be in use on July 1, 2025 and is now diligently removed. Initial improvements to the water surface should occur within a few days, although the current heat wave could shorten algae growth at short notice. Even if the oxygen content in the water is rated as good at 15 mg/l, the algae load the entire ecology of the pond.

measures to combat algae

In addition to the measures of the mowing boat, the influx of fresh water is reinforced by an installed standpipe. This is intended to help secure water quality in the long term. But the situation remains tense: a lower water level and dense plant growth expose the mowing boat to a high risk, since the screw has already been damaged twice. This clearly shows that it is not an easy undertaking to stop this annoying algae plague.

In times like this, the view beyond the Cologne city limits becomes important. The problem of harmful algae flowers (HABS) concerns many communities in Germany and beyond. According to Robeco there is a growing risk of water quality from algae flowers that exceed the capacity of many drinking water supply companies. Investments in modern water treatment systems and technologies to discover and destroy cyanotoxin cells are becoming increasingly urgent.

The problems on the Aachen pond are part of a larger topic that affects us all. Municipalities are increasingly being obliged to find suitable solutions in order to protect the quality and quantity of the water. It is to be hoped that the progress in combating the algae plague in Cologne is not only a temporary flare, but the beginning of sustainable changes in water management and care.