It comprises: a 20 x 5 m  radial gate, four 20 x 2,2 m hinged hatches, an 8 x 3 m log flume and a 95 m baffle wall. The rapids in Funnefoss in the Glomma river were used for mill operations, both flour and timber, as early as 1850. The paper mill, which was built in 1875, burnt down in 1877. However, a pulp factory was established at the same place. A smaller power station was built in 1919 to safeguard the power supply for the factories and the surrounding communities in Odal, in Akershus County.

During the last expansion, leading up to the start of the first turbine in 1975, the dam construction was combined with a road bridge. Rock material from the blasting while building the power station and the 440 metres long warping drain was levelled and filled with top soil. This resulted in 20 acres new farmland after the expansion.

Absorption capacity of the two tubular turbines is 440 m³/sec, while the flood diversion capacity of the dam is 3800 m3/sec. The spring flood in 1995 came close to this limit.

The preliminary investigations of the dam gates showed that the relations between the discharge flow and water level above the dam would not alter as a consequence of the expansion.