General description of the Bíobío Basin, Chile

The Bíobío River Basin , located between 36°45' and 38°49’ S and 71º00’ - 73º20’ W is Chile’s third largest river basin. It occupies an area of 24.371 km² (3% of the country’s continental territory) which stretches from the Andean continental divide in the east, on the Chilean-Argentinean border, to the Pacific Ocean in the west (Figure 1).

The basin belongs to a climatologic transition zone between temperate Southern Chile and Mediterranean Central Chile, and has a high value in terms of biodiversity, characterized by a considerable number of endemic species. At the same time, the area constitutes the country’s most important center for forestry activities, contains a major portion of the Chilean agricultural soils, and plays a predominant role in the national energetic supply (hydroelectricity). The basin has a total estimated population of 1.100.000 persons, of which 42% live in the metropolitan area of Concepción-Talcahuano. Only around 17% lives in rural areas.

Environmental issues

The Biobío River System serves multiple uses: besides its importance for the production of hydropower, as a source of water for industries, households, agriculture and recreation, and as a sink for urban and industrial effluents, the system’s integrity is also essential for the functioning of the local terrestrial and aquatic ecosystems.

Water balance, point and non-point source pollution

Considering the amount of industrial discharges and municipal effluents, the Biobío River is one of the Chilean water bodies most heavily loaded with contaminants. However, the actual implementation of waste water treatment technologies is likely to reduce the magnitude of the point-source problem in the near future. Due to the former, attention may gradually shift towards micro-contaminants from point-sources (pulp mills), not eliminated by the actually implemented technologies, to the problems caused by non-point source contamination, and to the largely unknown potential impacts of climate change and future development scenario’s on the local water balance and water quality.

The pronounced seasonality of rainfall highly influences the hydrology of the Biobío River System. The impact of flow regulation (hydropower) and water extraction (irrigation, drinking water, industries) on the summer discharges seriously influences water availability, as well as the effects of point source contamination on water quality. On the other hand, the regional topography generates a high potential for surface runoff and soil erosion during the winter period: surface waters in the region are known to receive important peak loads of sediments during high-intensity storm events. As a consequence of the former, fertilizers and pesticides used in agriculture and forestry activities may become important non-point sources of water contamination during winter.

Ecosystem degradation and loss of native biodiversity

The region’s ecosystems have been seriously impacted due to the combined effect of different human activities (forestry, agriculture, industry, urbanization). Harvesting, land use conversion and forest fires have severely fragmented and degraded the surface area still covered by native vegetation. The hydraulic regime and (local) morphology of the river system have been impacted by dam construction, arid extractions and irrigation practices, while their effects on the aquatic biodiversity remain largely unknown.

Stakeholders and integrated water resources management

More than 100 different stakeholders or stakeholder groups can be identified in the Biobío River Basin. Of these, the most important are: (a) the Chilean State, in its regulating and subsidiary role, as a promoter and as an investor; (b) the private sector, i.e. the different users of water and soil resources including the agriculture and forestry sector, the industries, power generating utilities, etc.; (c) civil society, i.e. social organizations, universities, indigenous communities, NGO’s and others.

The Chilean ‘Water Code’ or ‘Código de Aguas’ is the most important legal document related to water resources management. Its specific nature –through the free taxes and permanent assignation of user rights, the nation’s water resources acquire an almost private character– has promoted private, sectorial initiatives towards water resources management, while a more integrated approach remains largely absent.

Development of an integrated water resources management plan

The present twinning project aims at filling some of the previously cited knowledge gaps, while the possibilities for the implementation of integrated water resources management tools under the Chilean legislation will be further investigated.