The source of the river is found very close to this spot, the result of the flowing together of three springs that rise in Portela do Lagarto. We are, therefore, on the upper reaches of the Mouro where the river flow is still modest before increasing until it eventually joins the river Minho, in the neighboring municipality of Monção. The Mouro is one of the main rivers of Melgaço, being a permanent water course, although with a significantly reduced water flow in the summer. In the harsh winters the waters in its upper section can even freeze. The name of the river Mouro leads us, according to Pinho Leal, to the time of the presence of the Moors in the Iberian Peninsula, which, in this region, was never significant. In his book "Ancient and Modern Portugal", Volume 4, published in 1874, the author mentions that in this area a moor called Jusão had a hunting reserve. In the parish records there is reference to a priest saying that "a river called Mouro rises in the parish with its source in the Serra do Lagarto and that it flows gently through the midst of this parish, is crossed by the Bridge of Mouro, has three watermills (...)".