The Odelouca stream, together with the Arade stream, wetlands that in themselves hold great ecological value, among other tributaries, form the Arade river, considered the most important watercourse in the western Algarve. This “Arade River/Odelouca Stream” site can be considered a complex system of habitats, with different representations of the water resources available here (e.g. reservoirs, dams, springs, estuaries).

This diversity becomes extremely important in the richness of the species present and that are distributed according to the specificities of each location, highlighting its primary importance in the preservation of two species of fish endemic to the Southwest of Portugal, which have the status of “Critically Endangered” of extinction: the Southwestern boga (Iberochondrostoma almacai) and the Arade scaly (Squalius aradensis). Also associated with aquatic environments are the Mediterranean turtle (Mauremys leprosa) and the otter (Lutra lutra). Birds, in turn, find refuge and food here that are favorable to their presence, constituting one of the main attractions for nature tourism (e.g. Vale de Lama, Arrozal de Silves and Arrochela, Albufeira do rio Arade).

Following this aquatic system, a differentiation in the modeling of the territory can be noted, from upstream to downstream, where the embedded valleys, occupied by mountainous riparian galleries, characterized by the presence of willows (Salix alba), white poplar (Populus alba), oleander (Nerium oleander) and tamarisk (Tamarix spp.), give way to wide valleys, with accentuated estuarine characteristics as they approach the coast, interspersed with the flat banks typical of mangroves, with white grass (Halimione portulacoides) and madorneira-bastarda (Limbarda crithmoides), mudflats or small sandy beaches with agricultural areas.