Many of the water courses of the Canavese and of the area of Biella—the torrent Orco, for example—are noted for the presence of gold-bearing sands. In the case of the Orco these are concentrated in the area of the Bessa nature reserve.
Course
The river’s source is at an elevation of about 2,600 metres (8,500 ft) on the slopes of Monte Mars, in the heart of the Biellese Prealps. Having passed through various centres of population, it is joined from the right at Mongrando by its major tributary, the Viona. From here its broad pebbly shores follow the edge of the Bessa nature reserve, which lies to its right and is part of the Riserva naturale orientata delle Baragge.
Near Salussola it enters into the plains of Vercelli and follows a slower and more sinuous course before emptying into the Cervo near Quinto Vercellese.
Regime
The Elvo has a regime typical of a prealpine Italian torrent with maximum discharges in the autumn and spring together with a tendency to dry up in the summer and winter months. In the event of high levels of precipitation it is liable to become ‘torrential’.