Ecological improvement at Lake Mauren in Ehningen-Mauren

The artificially created Maurener See in Ehningen-Mauren is fed by two small streams, one of which flows into the Würm. This is home to a small population of stone crayfish, which is potentially threatened by the crayfish plague (occurrence of the camber crayfish) found in the Würm. The lake exhibited severe deficits in water quality (highly eutrophic plankton stage with severe water turbidity) due to silt deposits, heavy shading and the lack of macrophyte vegetation. The chemical analyses of the lake revealed very critical oxygen conditions in the course of the year, which gave rise to fears of the lake tipping over. This nutrient pollution also had a negative impact on the aquatic life of the stream below the lake.

The aim of the restoration and redesign measures was firstly to improve the water quality of the lake and thus its aquatic ecological properties; secondly, the stone crayfish population in the neighboring stream was to be protected from the introduction of crayfish plague and the habitat quality for the population was to be improved and thus sustainably supported. As part of the measure, the lake was completely drained and desilted, the banks were thinned out and shallow berms were created in future sunny sections of the banks, on which tall herbaceous, reed and macrophyte vegetation was initiated by planting. In addition, new regulating structures were installed to release stream water into the lake and to control the lake water level and the release of water from the lake to the Würm (overflow). These now allow flexible control adapted to the season and requirements (e.g. for future maintenance measures).

Two crayfish barriers were installed in the course of the stream according to the double barrier principle, which are intended to prevent the immigration of the camber crayfish. In addition, the structurally poor lower course of the stream was upgraded by means of slight bends in the course, the installation of crayfish shelters with flat stones (sandstone) and deadwood elements as a habitat primarily for the stone crayfish; however, other aquatic organisms also benefit from the redesign. All construction measures were carried out in compliance with special hygiene measures to protect the stone crayfish.

The importance of the lake as a popular local recreation destination was taken into account by creating a limited access area and by setting up information boards for visitors along the path alongside the lake and stream.

A comprehensive maintenance and development concept was drawn up to ensure the targeted development of the lake and stream.