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 km².