Ministry provides information on temperatures, oxygen levels, and algae formation
The measuring stations of the State Office for Environmental and Occupational Safety (LUA) at the Saar currently show expectedly high temperatures. They range in a critical area from 24.3 to 29.1°C. The highest value was recorded in Lisdorf. The temperature threshold for a good ecological status is 25°C. An improvement in the situation is not foreseeable due to the current weather forecast. Due to the high water temperatures and the increased pH levels, negative effects on the fish fauna are also possible.
On June 22, the LUA investigated the Saar River from Güdingen to Saarhölzbach regarding algae occurrence and found a local increase in the area of the Lisdorf reservoir. At the time of measurement, the second warning level for bathing waters set by the Federal Environment Agency concerning blue-green algae (> 24.0 µg/l) was exceeded with a measurement of 25.8 µg/l.
In the other area of the Saar, much lower concentrations of blue-green algae are observed (1.0 to 5.9 µg/l). For example, the highest value for total chlorophyll was measured in the Burbach area (67.3 µg/l). However, the proportion of blue-green algae in the total chlorophyll here is only 8.7 percent. The currently visible coloration of the water is due to a bloom of non-toxic green and diatoms algae.
Due to the strong algae development, there is an increase in pH values up to 9.6 (ideal would be 6.5 to 8.5) in Burbach, Lisdorf, and Rehlingen, as well as oxygen oversaturation of over 200 percent at an oxygen content of around 20 mg/l, so no critical oxygen values (< 3 mg/l) are expected in the coming days. However, excessively high oxygen levels can also be problematic, as they can cause bubble formation and respiratory problems in fish.
In Güdingen, Mettlach, and Saarhölzbach, the situation is still somewhat more relaxed. The temperatures and pH values are within a range compatible with fish ecology. The further development on the Saar is being closely monitored by the LUA.
The data from the measuring stations on the Saar can be viewed here.
