At any times rivers were lifelines and so important conditions for the origin of large settlements. Rivers gave us food and drink, were important transportways and energyboosters.

In the Middle Ages in Erfurt water mills were located on several tributaries of the river Gera. On the river above all building timber from the Thuringian forest was floated up to the town. But the river Gera was also a sewer. At the latest by the next high water all rubbish was taken away. In the course of the centuries the tributaries were extended for the defence, for the water supply as well as the sewage disposal. The names (for instance "Gerberstrom " = "tanner's stream " point to the original appropriation; they are important witnesses of the urban development.

Running waters in towns are mostly intense narrowed down. Their flow is regulated and shortened or was layed wholly under the earth. Inspite of the build of new sewage works large quantities of waste water will dump in the rivers. The follow of increasing ground-sealing of urban areas are periodical but extremely flowing offs after rainfall.

For these reasons only relative poor species live also in lifelike sections. Nevertheless these areas are important biotopes of the town. As "green band" they realize the contact between the town and the environs and make the migration from several animal species to the town possible.

The European water vole is the largest of the native voles. They mostly live subterranean in self-built burrow-systems. Every vole has its own burrow-section, which is defended against other animals of the same species. The burrows are constantly extended and modified by scraping. The digged out hills are similar to the mole-hills. European water voles mainly live on subterranean plants. Often you can meet them near water areas. That's why they are called "Earth vole" and "water vole".

The Kingfisher needs water, rich in small fishes and of a good deep-sight. Overhanging wood on the bankline is used as observation point. From those points the Kingfisher swoops down and captures fishes and water-insects. Its nest is in a breeding tube. The bird builds it in broken down edges of the steep banks. The extension of the waters strongly reduces the living possibilities of the "flying jewel".

Minnows are lively, in shoals living small fishes. They live mostly in clear and cold running wates, rich in oxygen and in lack of nutrients lakes. For spawning they go to sandy and gravel places. During the spawning time the Minnows belong to the most colourful fishes in our waters. Because of the extension of the waters the Minnows are endangered in their existence.