|Dam and spillways|
|Type of dam||Embankment dam|
|Height||44 m (144 ft)|
|Length||180 m (591 ft)|
|Dam volume||1 hm3 (35,000,000 cu ft)|
|Total capacity||124 hm3 (4.4×109 cu ft)|
|Catchment area||1,100 km2 (420 sq mi)|
|Surface area||6.6 km2 (2.5 sq mi)|
|Installed capacity||7 MW|
In the 1920s, several hydropower plants were built in the tributary of the upper Isar river such as ones at the Achensee and Lake Walchen Power Plant. Therefore, the river ran nearly dry during the dry season, and the low water flow affected the town of Bad Tölz. A reservoir was established to ensure a minimum level of water in the river. During the dry season a volumetric flow of 4 cubic metres per second is released to prevent the Isar from running dry. Additionally, the reservoir provides flood control for Isar river between Bad Tölz and Munich.
The dam is 44 metres (144 ft) high and 180 metres (590 ft) long. It was built between 1954 and 1959. From 1959 on, the water was also used to operate a hydropower plant of 3.2 MW. The plant was upgraded in 2000 with new turbines to generate 3.8 MW.
During the 2005 European floods, the maximum capacity of the reservoir had been reached. Consequently, excessive water was released into the Isar river. If the dam hadn't been built in the first place, the flooding would be more severe.