Anterior Rhine in the context of Rein da Medel

The Alpine Rhine Valley (German: Alpenrheintal) is a glacial alpine valley, formed by the Alpine Rhine (German: Alpenrhein [ˈalpm̩ʁaɪn] ), the part of the Rhine between the confluence of the Anterior Rhine and Posterior Rhine at Reichenau and Lake Constance. It covers three countries, with sections of the river demarcating the borders between Austria and Switzerland and between Liechtenstein and Switzerland. The valley is 93 km long. In the upper 9 km stretch, the valley width is 1.5 km with narrow (60 m) incised channel. For the next 71 km, the valley floor varies between 3 and 4 km; on approach to Lake Constance the valley widens up to 15 km.

Lai da Sontga Maria (Italian: Lago di Santa Maria) is a lake, located north of the Lukmanier Pass in Switzerland. It lies almost entirely in the municipality of Medel (canton of Graubünden), a tiny fraction of the south-west part of the lake belonging to the municipalities of Quinto and Blenio (canton of Ticino). The reservoir has a surface area is 1.77 km (0.68 sq mi). The arch dam Santa Maria, which is to the north of the lake, was completed in 1968. The main road of the Lukmanier Pass runs along the eastern shore of the lake.

The lake lies at a height of 1,908 metres above sea level and is surrounded by mountains over 3,000 metres on both sides. The highest peak overlooking Lai da Sontga Maria is the Scopi (3,190 m), on the east side. On the west side are Piz Gannaretsch (3,040 m) and Piz Rondadura (3,016 m). On the south side (in Ticino), the lake is overlooked by Pizzo dell'Uomo (2,663 m). The lake is drained by the Rein da Medel, a tributary of the Anterior Rhine.