The Liro is an Alpine torrente of the north Italian Province of Sondrio which rises near the Splügen Pass and the boundary with Switzerland. It runs the length of the Valle Spluga (or Val San Giacomo) before joining the Mera from the right at Prata Camportaccio, a little southwest of Chiavenna. At the upper part of its course by Montespluga it forms a small reservoir, the Lago di Montespluga, elevation . It forms a second, and still smaller, lake at Isola.