Water okay, but fishermen worried about Dietlhofer See: Then "it won't exist in 50 years"

Created: 06/18/2022, 02:00 p.m

By: Katrin Kleinschmidt

A popular place to switch off for many Weilheimers is the Dietlhofer See.

But the fishing club is worried about the water.

© Emanuel Gronau

Fishermen are worried about the Dietlhofer See.

Because they sounded the alarm, the water quality was checked in 2021.

That's fine.

The topic is not off the table.

Weilheim

- Fewer and fewer water lilies, disappearing fish species, but in the depths more and more mud and the smell of sulfur.

The fishing club Weilheim is concerned about the Dietlhofer See and drew attention to it in 2020.

At a meeting with Ullrich Klinkicht (responsible for the lake on the city council), representatives of the water rescue service and the Conger scuba diving club, it was decided with the Weilheim water management office that the water quality of the lake should be checked.

The results are now in.

And brought no explanation for the phenomena observed by the fishermen.

Compared to earlier values, "the fear of a deterioration in water quality expressed to us has not been confirmed," says Bernhard Müller, department head for the district in the Weilheim Water Management Office (WWA).

The authority last took and analyzed samples in 2004 and 2009 to learn about the condition of the lake.

The inspection of the WWA is mainly about flora and fauna.

In order to rule out any danger to humans, the "Dietschi" is also regularly checked for bacteria by the health department.

This year already twice - always without complaint.

Samples were taken from Dietlhofer See for a year

And the WWA is also satisfied with the water quality.

In the past year, it had samples taken from the deepest part of the lake almost every month - and in the process gained insights into the condition of the lake at different depths.

For example, a “significant improvement” was found in the overall phosphorus.

The chlorophyll values ​​in 2021 were also slightly below those of earlier measurements, "which indicates a lower plankton density and also caused measurably greater visibility depths," explains Müller.

“On the other hand, nothing has changed in terms of the unfavorable oxygen conditions.

In late summer there was still no oxygen available below a depth of five to six meters”.

All in all, it can be stated that the water quality in the depths of the lake has not deteriorated since 2009.

"A general trend towards improving water quality" cannot be derived from the results, emphasizes Müller.

The study period of one year is too short for this.

Over the years, there have been strong fluctuations due to the weather and external influences, such as agriculture.

But one thing is clear: the disappearance of the water lilies "must have other causes, it's not because of the water quality," says Müller.

For the WWA, "the topic is closed".

City must "get into the slippers"

Not for the fishermen.

Stefan Schröpfer, Managing Director of the Weilheim Fishing Association, leaves no doubt about that.

"There is nothing missing from the water," he notes.

"The basic problem that the lake has is not off the table." The lake has lost enormous depth in recent decades.

While in the 1970s there was still talk of about 24 meters, the bottom of the lake is now only about 18 meters below the water surface.

The fishermen are also worried about the layer of mud on the bottom, a carpet of bacteria found by the divers at depth and, according to Schröpfer, around 20,000 cubic meters of rock, rubble and earth that have been washed into the lake by heavy rain in recent years.

"If things continue at this rate, the lake will no longer exist in 50 years," Schröpfer fears.

The city must “get into the slippers.

At some point you have to do something good for the lake”.

Schröpfer could imagine that sludge would be sucked out or that oxygen would be added to the lake.

He wants to get in touch with Klinkicht and collect ideas with him.

"Maybe he can check what work is eligible for funding."

Schröpfer regrets that the city has not yet tackled the issue with particular urgency.

"Unfortunately, if you can't cement something in concrete, it's not worth that much in Weilheim," he says sarcastically.

But the Dietlhofer See is a “gem.

I think it's worth preserving."

It's certainly not just the fishermen who see it that way.