Stausee Solis

The Stausee Solis ("Solis reservoir") is a reservoir on the Albula river, located between Alvaschein, Stierva and Tiefencastel, in the canton of Graubünden. Its surface area is 17.75 ha (43.9 acres). Was built in 1986 by the Electric Power Company of Zurich (ewz). Until 2012 about 50% of the reservoir volume of 4.1 million cubic metres (3,300 acre⋅ft) got lost due to sediment aggregation. A dam of 61 m (200 ft) height and a crown length of 75 m (246 ft) holds back the water in the lake. The water in the reservoir is used for energy production further downstream, in the power plants Sils and Rothenbrunnen. This dam is used as daily storage. Due to the low ration between lake volume and catchment area the sediment aggregation plays an important role. Around 100,000 m³ (3,500,000 cu ft) of sediment settles down every year in the lake. In 2012 a sediment bypass tunell (SBT) was built, which operates only a few days every year, but provides sedimentation almost completely in the reservoir. But there are many investigations due to abrasion in the tunnel to make.

Stausee Solis
View from the Rhaetian Railway line
Location	Alvaschein/Stierva/Tiefencastel, Graubünden
Coordinates	46°40′25″N 9°32′38″E
Type	reservoir
Primary inflows	Albula
Primary outflows	Albula
Catchment area	900 km2 (350 sq mi)
Basin countries	Switzerland
Surface area	17.75 ha (43.9 acres)
Water volume	4.1 million cubic metres (3,300 acre⋅ft) (1986) , ~1.5 million cubic metres (1,200 acre⋅ft) Mio m3 (2012)
Residence time	0.008 years
Surface elevation	824 m (2,703 ft)
References	Swisstopo[1]

The dam is located just east of the Solis Viaduct of the Albula Railway.