Source of the Nela river Nature · Valdeporres, Las Merindades, Burgos Image of Valdeporres, not of the place itself. The Nela rises in the montes do Somo, within the municipal area of the Merindad de Valdeporres, and runs for 75 kilometres before flowing into the Ebro near Trespaderne, after passing through Puentedey, where it has bored through the rock arch on which the village sits. Its flow mainly supplies the towns of Villarcayo, Medina de Pomar and their hamlets. Two stretches of the river, together with stretches of the Trema and Salón rivers and several tributary streams, form a 679-hectare Site of Community Importance at the northern edge of the province of Burgos, which includes the valley of the río de la Gándara, with a series of stepped waterfalls known as Las Pisas. Its wildlife includes the kingfisher, the Pyrenean desman and the otter. Photo: Cronoser (CC BY-SA 4.0) What to see and do in Valdeporres