The Isar river enters Germany near Mittenwald and flows through Bad Tölz, Munich, and Landshut before reaching the Danube near Deggendorf.

The official source of the Isar is located in the Hinterau valley east of the village Scharnitz in the Karwendel mountains at a height above sea level of 1160m.

Not far down the Isar river is a large reservoir called Sylvensteinsee was created between 1954 and 1959 to make more energy generation possible and also to avoid flooding.

Further downstream, the river passes Freising, then the Amper flows into the Isar, its most important tributary, at Moosburg.

[citation needed] Among Central European habitats, Alpine rivers are ranked among those most substantially altered by humans over the past hundred years.

[citation needed] Industrialization gave rise to a sociotechnical system were the Isar River was economically exploited through multifunctional use.

[4] Following their executions on October 16, 1946, the ashes of the convicted Nazi war criminals Joachim von Ribbentrop, Hans Frank, Wilhelm Keitel, Alfred Jodl, Alfred Rosenberg, Ernst Kaltenbrunner, Wilhelm Frick, Arthur Seyss-Inquart, Fritz Sauckel, and Julius Streicher were scattered in the Isar, as were those of Hermann Göring who had committed suicide the previous night in defiance of his scheduled execution.

Embankments were removed and the river bed was widened, establishing connections to surrounding flood plains.

Since 1990, a small portion of the water, 4 cubic meters per second (roughly 1,100 U.S. gallons per second) is allowed to remain in the river Isar to prevent drought.

The construction of the Sylvenstein Dam and numerous regulations relating to the river, pushed through in the early 19th century, have strongly enhanced its character.

The riverbed is being widened, the banks are flattened and small gravel islands are built along with near-natural rock ramps to slow the waterflow.

This first civil initiative from Munich purchased 90 ha of land, and today maintains more than 330 km of hiking trails.