Historical changes,and a modern program to improve the ecology of the Alster River of Germany

The Alster River, located in and around the State of Hamburg, Germany, is an extensively polluted, urbanized river of historical importance currently experiencing a cleanup effort of unprecedented proportions. The 30-year projected sewerage renovation currently in progress is designed to protect the river's water quality and is estimated to cost overall in excess of 1 billion DM (German marks). In this paper we analyze the in-progress construction of a modern sewerage network to restore the Alster River quality. To understand the importance of a new sewerage system it is necessary to review the history of the Alster River following urban settlement that began in the ninth century at the confluence of the Alster and the Elbe at the site of Hamburg. The biological and physical changes affecting communities of the Alster ecosystem are reviewed, as well as the developmental history of impoundments and canals along the river and the development of the sewerage system of Hamburg in relation to the Alster. The plan for restoration of the Alster is one of the most dramatic of its kind in modern European history and provides a blueprint for similar urban river restorations worldwide in the future.