Unisee: Measures to improve water quality in the Stadtwaldsee

Unisee: Measures to improve water quality in the Stadtwaldsee

in the Stadtwaldsee, better known as Unisee, the water quality has been in the focus of the Advisory Board of the Horn-Lehe advisory board for years. In recent years, the problem of increasing blue -green algae has been pointed out, which led to demands for measures to improve water quality in 2021. Now the environmental authority has submitted a limnological report that illuminates the background of this development and how to improve the situation.

Martina Völkel from the environmental department reported on the findings of the investigations. The main cause of algae growth in the Unisee is an increased phosphorus content in the water that acts as a nutrient for blue algae. A basic measuring program showed that the problems during winter and early spring are most serious and that the water becomes particularly cloudy during this time. This cloudiness harms the development of aquatic plants, which play an important role in reducing phosphorus in the lake. The lack of these plants leads to a vicious circle that further deteriorates the water quality.

influences on the phosphorus content

The causes of the high phosphorus content are complex. One of the main factors is the carp and bream that hinder the growth of aquatic plants due to their guns in the sediment. It is also checked whether phosphorus gets from the groundwater into the lake, which requires further examinations. In addition, careless bathers contribute to contamination by not using the sanitary facilities provided.

The planned measures to combat the problem are extensive. Kerstin Kunze, who explained the progress, reported that the cooperation with the Sportfischer Association has only brought about limited success to reduce carp. Nevertheless, this partnership should be continued. In addition, various approaches to promote aquatic plants are intended, especially in the bank area of the nudist beach, which will in future be protected from impairments by fences and bojets.

planned interventions for improvement

In order to prevent erosion on the banks, further security measures are necessary. These include, among other things, the use of vegetation rollers that are intended to help the aquatic plants. In this regard, parallels must be drawn to previous projects in which dead wood bundles were sunk in the UNISE to improve the underwater conditions. In order to improve the hygienic conditions for bathers, an increase in sanitary facilities is also considered, which, however, turns out to be difficult due to costs and maintenance issues.

Another strategy for reducing the phosphorus content could be the targeted phosphorusishaben, in which certain chemical substances are used to bind phosphorus in the water. Tim Epe explained that by the correct selection of these substances, such as aluminum salts, a permanent impairment of the water quality can be avoided. Before this measure is implemented, however, it must be ensured that the groundwater has no phosphorus loads in order to avoid repeated interventions.

Overall, the steps to improve water quality in the Unisee are to be regarded as complex, and the institutions and experts involved are actively working on solutions to ensure the health of the popular local recreation area. Additional information and details on the planned measures can be found in a report on www.weser-kurier.de .