Imagine M\u00e4ander, backwaters, and unique habitats. This is Altrhein Maxau. It is a nature reserve in Karlsruhe’s west, part of the Altrhein area. Burgau, a younger nature and landscape reserve, surrounds it.
Altrhein Maxau spans approximately 35 hectares in the Knielingen district. It includes the northern part of the Knielinger See. The area borders the fields of Hofgut Maxau to the west. To the north, the Winden-Karlsruhe railway line marks its boundary. The Leimengrubengrund, part of the Karlsruhe city forest, lies to the east.
Altrhein Maxau connects to the Burgau nature and landscape reserve. Altrhein Maxau became a protected area in 1980. Burgau followed in 1989. The area is also an EU bird sanctuary. It is part of the Rhine lowlands between Elchesheim and Karlsruhe. It is a special area of conservation. This is the Rhine lowlands between Wintersdorf and Karlsruhe. It is part of the Natura 2000 network. The LIFE project created it. It is called “Living Rhine Floodplains near Karlsruhe.”
The Altrhein Maxau protects the Altrhein. M\u00e4anders are found here. They remained as side arms. This happened during natural shifts in the Rhine’s riverbed. The area protects typical siltation communities. It also protects woodland zones.
The existing ecosystem is protected and developed. It is home to rare and endangered species. These species live in the Rhine floodplain. The area serves as a regeneration zone. It benefits the directly connected Maxau gravel pit lake.
Professor Dr. K\u00fchlwein from the Botanical Institute Karlsruhe helped protect the Altrhein Maxau. On February 8, 1963, he requested the Knielinger See be declared a nature reserve. The focus shifted to Altrhein Maxau. He based his request on the ecological value. He also cited its suitability as a treatment plant for the lake.
Markgraf Berthold von Baden owned Altrhein Maxau. He had approved gravel extraction there in 1957. Protection required his consent. It also needed changes to the gravel extraction agreement. Negotiations with the Markgraf’s representatives followed.
In 1970, the city seemed to have settled fundamental issues. In Strasbourg, a European nature conservation conference took place. It stirred up the garden department. On January 8, 1971, the department questioned the validity. They wondered if the standards for gravel extraction still applied. This was after 1.5 decades.
In early 1971, the Markgraf made new demands. The city went public. The official process began. It went through the planning committee and the city council. The committee met on May 14, 1971. The garden department distanced itself. It had initially embraced the nature conservation conference. It prioritized the bathing lake and Rheinstadt projects. These required preserving Katersgrund island. Professor K\u00fchlwein advocated for preserving shallow water. It was west of Altrhein Maxau.
Compromise was found. The council members met at the Knielinger See. They agreed to Variant 3. This included both concerns. The city council approved Variant 3 in early July 1971. This ended years of discussion. The Markgraf approved.
The city invested much in protecting Altrhein Maxau. It involved negotiations and additional expenses. The city covered removal costs. This was for the overburden from the new dredging area. It was southeast of the lake. The city relocated the Federbach. The gravel plant contributed 150,000 DM. In 1980, Altrhein Maxau became a nature reserve. This corrected the 1957 decisions.
Altrhein Maxau faces challenges. The shallow water zone tends to eutrophication. The reed belt is shrinking. Thirty years ago, reeds covered large areas. Now, only remnants remain. Inside the Entenfang, reeds have disappeared. This indicates high nitrogen levels. The decline in reed affects the biological quality. It impacts the breeding of great crested grebes.
The absence of water chestnuts raises doubts. It questions the listed species. It suggests a need to update assessments. Currently, widespread reed dieback requires replacement sites. The protection of this area, Altrhein Maxau, relies on this biotope type. Preserving this natural treasure ensures its ecological role remains intact for generations to come.