In the Loisach some measures will have to be taken in the coming years to improve the habitat of the fish.
There will also be talks about relocating the Moosrundweg in Benediktbeuern.
That is an area of tension.
A drastic decline in fish diversity was noted in the Loisach
Therefore, some things should be improved for the population of the animals
The closure of the Moosrundweg at the Benediktbeuern monastery remains
Kochel am See / Benediktbeuern
- As part of the European Water Framework Directive (WFD), all lakes and rivers in Europe must be in good condition by 2027.
The German water management offices have been working on the implementation since the turn of the millennium, in prescribed time intervals of several years.
Most recently, a wide variety of data was collected from 2009 to 2015 and from 2016 to now in order to create a catalog of measures based on this.
The good news first: The Loisach achieved good scores in many points in the section between the Kochelsee and the confluence with the Isar near Wolfratshausen, report Robert Kapa (Head of Biology and Coordinator of the WFD) and Marina Brunner (landscape planner and employee in the area of water development) from Weilheim water management office on request.
Both the microorganisms in the water and the aquatic plants and algae on the bottom of the river as well as the water quality are in good condition (level two out of five).
In the case of nutrients and pollutants, too, no exceedances were found in the study periods.
The fact that the Loisach only achieves level three in the overall rating is due to the interplay of water structure, runoff behavior and the associated problems for the fish, explains Kapa.
At the beginning of the 18th century the river was expanded.
Today it has been straightened, experts speak of a "box profile".
The Loisach has also changed with the construction of the Walchensee power plant.
Because of the transfer, more water is fed to the river from the Isar region.
“Today we have a lot more water in the Loisach than originally,” says Kapa.
The current structure of the river bed has little in common with the original state of the river.
Drastic decline in fish species
However, the more water that flows away, the greater the impact on the habitat of the juvenile fish.
"The Loisach originally had a species-rich fish fauna," reports Kapa.
There used to be 20 different species here, also due to the numerous tributaries.
However, the experts at WWA have noted a drastic decline in species.
Among other things, this is due to the fact that the Loisach is deepening and floodplains are only rarely flooded.
In addition, the river lacks the network with side waters and oxbow lakes where young fish can grow up.
“We don't want to achieve the natural state of the Loisach, but we want to give the river more space,” says Brunner.
In the course of the Water Framework Directive, it is a matter of ensuring the survival of the fish and the various "quality components" - i.e. the good condition of the other areas.
Therefore, a catalog of measures is currently being worked on, which will probably be presented at the end of the year.
The WWA wants to create near-natural structures in the bank area and in the river bed.
In addition, permeability for fish must be guaranteed.
There are at least nine transverse structures that are not permeable.
Kapa cites the Schönmühl power plant as an example.
There is a fish pass here, but it doesn't work so well.
“The fish won't find them.” In addition, the passability of the Loisach loop must be improved in this area.
The power plants in Eurasburg and Weidachmühle would also have to be made seamless.
Deadwood helps fishing
The experts at WWA are also planning various restoration measures.
For example, the bank petrification should be removed in some areas.
In addition, they want to bring in dead wood so that the fish have shelter and the young fish have protection from predators.
A third step is the better connection of oxbow lakes and tributaries, such as the Lainbach near Benediktbeuern and the Bierbichl low arm south of Königsdorf.
In such areas should "move back to life".
The catalog of measures is discussed with the other authorities, municipalities and property owners.
Kapa expects a "long coordination process".
The WWA has little land of its own, and in many cases the river borders on agricultural land.
Where possible, a purchase will be negotiated, says Kapa.
In many cases, however, it will result in measures being taken in the river bed.
According to the WFD, the “good biological status” must be proven by 2027.
The two experts at WWA describe this as “ambitious”.
It's not just about structural changes to the power plants, but also about the response time of biology.
The population must first expand again, and that must be monitored and documented over a longer period of time.
Part of the Moosrundweg at Benediktbeuern Monastery remains closed
An implementation concept is currently being developed for the situation on the Moosrundweg at the level of the Benediktbeuern monastery.
The path - a piece runs close to the river - has been partially closed since March 2018, but only a few day trippers pay attention to this, and the warning signs are often even torn off.
Between the outflow Kochelsee and the bridge over the B 472, the river “nibbles” on the bank, so it wants to expand its bed.
After heavy rain, precipitation or flooding, the acute danger is greatest, because then the bank area is weakened.
“The path remains closed,” says Marina Brunner.
The Loisach has a strong momentum of its own.
"The river looks for its way, the barriers then collapse." From the point of view of water management, this is desirable.
The current course of the Moosrundweg does not necessarily have to be preserved, says Robert Kapa.
But he also knows that relocation will collide with other nature conservation concerns, such as the habitat of meadow breeders.
"There is still a lot of coordination to be done here."
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