Things are moving in the Freihamer Au floodplains

21.11.2012Wasserburg am Inn

VERBUND Innkraftwerke GmbH is commencing the restructuring in the reservoir area of Wasserburg and the Freihamer Au floodplains

VERBUND, Austria's leading electricity company and operator of the Bavarian Innkraftwerke plant is continuing the measures begun in the last winter half year for the improvement of the water structure. The basis for this is the agreement between VERBUND Innkraftwerke GmbH and the Bavarian State Ministry of the Environment and Public Health, which consists in a partnership lasting several years. The renaturation measures contained within also include, among others, desedimentation and connection of backwater to the main stream, creation of breeding islands for rare bird species as well as spawning grounds for fish and amphibians. Ecological accessibility to reservoirs will be established by 2015. This is to ensure that ecological deficits are identified and mended and valuable sections of the river landscape cared for and improved. The measures were begun in October and will be completed in the course of the winter.

"In the course of our acquisition of the Inn power plants we agreed to reinforce our long-standing partnership with the region by implementing appropriate measures," is the information divulged by Karl Heinz Gruber, CEO of VERBUND Innkraftwerke GmbH. "As one of the largest operators of hydropower plants, we are aware of the responsibility for the delicate water habitats around the Inn."

At the time, this was sealed by agreement with the Bavarian State Ministry of the Environment and Public Health. "From the very beginning, we were open to the proposals of the State Ministry of the Environment and Public Health regarding improvement of the ecological system," Michael Amerer, CEO of VERBUND Innkraftwerke, explains. "And we're happy to be able to maintain the Freihamer Au wetlands as a valuable refuge for all types of species and nature in general and to upgrade its value through the measures passed by us."

"We want to create new valuable structures there and again increase the diversity of species which, due to sedimentation of the somewhat monotonous reed bed, has suffered significantly," says VERBUND project manager Georg Loy. Loy points to the two bird islands that have already been established and practically taken over by the common tern, a swallow very rare to Bavaria, as a nesting place. "Successes like that for the diversity of species encourage us to pursue the path taken," Loy emphasises.

For this reason, the Freihamer Au wetlands will soon be invaded by excavators including a dredger. New water areas are to be created, water ways established between the backwater and the river Inn, as well as crude soils created in the wetlands. "These are exactly the structures that, over the past years, disappeared from the Freihamer Au," explains Christoph Stein of Planungsbüro Schober (agency of urban planning), who has been assigned the task of carrying out ecological pre-inspections and planning measures. "With the help of old aerial and field photographs, we were able to reconstruct almost exactly the condition of the Freihamer Au of the 1970s and the 1980s," Stein continues. "The stringency of the measures thus became transparent. What was known as pioneer stadia has disappeared almost completely, however, these are particularly valuable locations for rare plant and animal species in the wetlands."

Fish and mussels
Valuable experiences and first measures were also contributed by the fishing union of Wasserburg. A number of years ago already this association started with sedimentation of backwater areas and the reconnection of the same to the river Inn. "We are thrilled to be able to now carry on with more comprehensive upgrade measures," Franz Göpfert, First Chairman of the fishery union explains. The members of the fishing union, but also that of the neighbour fishing union in Rosenheim, have all agreed to actively support the work.

Thus, before the commencement of dredging, the mussels have to be extracted from the mud floor of the backwater areas. This has been stipulated by the nature conservation authority. Katharina Stöckl of the mussel coordination office at the technological university in Munich says, "The mussels are discovered by hand and brought to an interim husbandry. After dredging, they are returned to their original position." The measures also constitute an improvement for the mussels. "Wherever new water areas are created and deep regions are fashioned, mussels can multiply and grow into larger populations than before," says Stein. "Since the waters are becoming more attractive again for the fish, there will also be better conditions for mussel reproduction since mussels are largely dependent on fish."

Measures were begun in October and will be completed in the course of the winter. "Hence, the works will take place during a time of the year in which no great disturbances are to be expected for the bird world, for example," says Loy. In order for the ecological goals to be reached in an optimum manner, ecological construction supervision has been envisaged to keep in constant touch with the nature authorities in charge. Loy further says, "We know that the Freihamer Au wetlands are a valuable nature conservation area and is much esteemed by the population of Wasserburg. Thus, we want to contribute to maintaining this area and also revitalising it.

History of the sedimentation of the Freihamer Au wetlands
At the gates of the Inn city of Wasserburg lies the well-known nature conservation area of the Freihamer Au. It was established in the 1930s through the damming up of the river Inn by means of the construction of the power plant of Wasserburg. Old maps show that, in the location of the current nature and bird conservation area next to the Inn branches, there also used to be agricultural soils and fields and meadows. As a result of the plant construction and the up-damming, the water level was raised a few metres and backwater areas, sedimentation reed beds and floodplain forests came into being.

Over the last decades, an increasing degree of sedimentation has taken place. The sand masses brought along by the river deposited quickly and were rapidly overgrown with reeds, phalaris arundinacea (reed canary grass) and willows. The previously large water areas became smaller and smaller to the extent that some have grown over altogether. In addition, in some places the direct connection to the river Inn was lost, so that fish were no longer able to cross between river and backwater. Recently conducted inspections revealed that what might have appeared to the eye as an untouched paradise actually held a number of deficits for fish species, birds and plants home to the river and mud banks.

Cooperation with all involved parties
The package of measures allotted for 2012 was passed in close cooperation with all involved authorities, the water authorities and district office of Rosenheim, the provincial government of Upper Bavaria, associations, as well as the specialist association and fishing unions. In part, projects initiated by the fishing unions were also adopted. All measures are in compliance with the conservation goals of the FFH area.

VERBUND Innkraftwerke GmbH employs some 200 employees, male and female, and operates 13 run-of-river plants on the Bavarian river Inn with a total capacity of 312 megawatt. The annual output amounts to 1.8 billion kilowatt hours, which corresponds to the requirements of more than 470,000 households. This quantity of hydroelectricity also means a reduction of more than 1.5 billion tons of CO2 per year, measured against a modern hard coal plant.


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