BONN Fish and waterfowl have perished in the Rheinaue Lake this summer, with the water having an inadequate oxygen supply. As a result, the city plans to rehabilitate the lake. A Meckenheim company has proposed to cleanse it with microorganisms.
Because of the fish and water fowl dying in the Rheinaue Lake this summer, the city administration commissioned several studies to investigate the causes. As a consequence, the Rheinaue Lake is to be rehabilitated in mid-2020. An institute is currently taking samples from the lake to develop a concept for biological restoration. Part of the plan is for samples to be taken regularly through the autumn of 2019. The city bureau in charge of urban parks said it was necessary to collect data over a longer period of time and in different seasons.
Using microorganisms costs less than dredging
A concrete plan for lake restoration is to be drawn up at the end of next year. Implementation will start in mid-2020. The costs are included in the budget for the years 2019/2020.
Emiko is a firm located in Meckenheim and it’s managing director, Christoph Timmerarens, said he has offered to restore the lake using microorganisms. In that process, effective bacteria would be introduced into the mud layer. Timmerarens also said that two professors from the University of Wuppertal and Koblenz are interested in supporting the project scientifically.
The city of Troisdorf already has experience with this process using microorganisms, the firm Emiko having used it on a pond in a bird park there. The work took two days and cost less than 10,000 euros, while "A conventional dredging would have cost 50,000 to 60,000 euros," said the city of Troisdorf. Initial cost estimates from Timmerarens for treating the Rheinaue Lake come in at around 120,000 euros. To dredge the lake, the city would have to expect costs of around 500,000 to 750,000 euros. "And ours is the more environmentally friendly option," says Timmerarens. An underwater vehicle would distribute the bacteria to the mud layer over two weeks.
Hundreds of fish died
Timmererans says his company has carried out similar lake restoration in Bavarian swimming lakes, in a moat at a castle in Lower Saxony, and in a lake in Mannheim. The city administration will not comment on proposed restoration methods until it has the full analysis with proposals from the commissioned institute.
Since summer, several hundred fish have perished in the lake, along with over twenty waterfowl. In July, city employees collected four dead waterbirds, along with nine in August and eight in September. Passers by rescued an injured heron from the lake when it was apparently no longer able to free itself from the mud layer on the ground.
(Orig. text: Sabrina Bauer; Translation: ck)