On 29 February 1988, the Consorci for the Defense of the River Basin of the Besòs River was constituted with the approval of 25 municipalities in this basin and the Metropolitan Entity of Hydraulic Services and Waste Treatment, of its Statutes (published in BOP No. 190, of August 9). These statutes confer on the Consorcio an administrative nature and full legal personality to fulfill its objectives. Since 1993, it is registered in the Register of Local Entities of Catalonia, with identification code number 9800960009.

On June 29, 2016, the General Board of the Consortium carried out a modification of its statutes to extend the scope of action of this entity to the municipalities of the La Tordera basin, going on to be called the Besòs Tordera Consortium . With this modification, voluntary membership is allowed to the Consortium of any municipality in this basin.

Currently, the Consortium is made up of 68 entities, of which 64 are municipalities of the Barcelonès, Osona, Vallès Occidental and Vallès Oriental, with a population of around 2,400,000. The rest are the Diputació de Barcelona, ​​the Metropolitan Area of ​​Barcelona, ​​the Consell Comarcal del Vallès Oriental and the Consorci per a la Gestió dels Residus del Vallès Oriental.

The lines of action of the Consortium are the sanitation in the low (municipal sewers), the sanitation in high (control of plinths, collectors, pumps and wastewater treatment stations - EDAR's-), the improvement of the river environment, the promotion and environmental education and the support to the consortiums.

Of these 64 municipalities, 51 have delegated to the Consortium their functions as an administration acting in the field of sanitation, with a population of the order of more than 500,000 inhabitants and more than 4,000 potential contaminant industrial establishments implanted.