A non-navigable river, the Besòs was nonetheless a link between the Catalan coast and the interior. In the 10th century, the Rec Comtal was built to use the river for irrigation.
In 1962, the river along with Llobregrat river overflowed causing a flood in many areas of the Vallés Occidental and to a less extent in Vallés Oriental and Barcelonés. The flood caused many deaths (617 according to the official death toll and up to 1000 according to some estimates) and material damage.
As it passes through a highly industrialized area (Barcelona metropolitan region), it had the dubious honor of being the most contaminated river in Europe during the 1970s and 1980s. Since the mid-1990s, however, the river has been in the process of recovery.