The Rio Lima Site is divided into 5 counties, corresponding to the area within the limits of the municipality of Viana do Castelo, about 35% of its total area. In this county, the valley of the Lima river is quite open, and its wide and flat margins are framed by an agricultural landscape, punctuated with galleries and little woods.
With the entrance in the estuary, the river widens and in the middle of its bed small insholes with typical vegetation of marsh emerge. The human occupation is intense throughout the zone, but diffuse. Despite this, and especially in the upstream sector of the estuary, the natural space presents a remarkable degree of conservation. The sapal-juncal complex there is of particular relevance and is integrated into the high estuary.