The particularities of water management in a metropolis: Bordeaux or the “cooperative metropolis”

The question of water, a story of political and technical cooperation

Until 1945, the Girondin supply of drinking water was ensured from surface resources. The Bordeaux conurbation was then subject to recurrent water shortages which lead him to look for water ever further from his walls. As soon as the war ended, a new model emerged. It is based on the creation of boreholes in the deep aquifers which today provide more than 75% of the department’s drinking water.. The proliferation of boreholes and the continuous increase in withdrawals led scientists from the Bordeaux school of hydrogeology to wonder as early as 1956 about the risk of overexploitation of these high inertia aquifers, the functioning of which was then very poorly understood.

At the end of the 1990s, the exercise, widespread at the time, of drawing up a departmental drinking water supply plan provided an opportunity to confirm the overexploitation of certain groundwater and to propose technical solutions to remedy. Given the stakes, the complexity of the subject, and the investment costs to be agreed to relieve the overexploited aquifers, the department and the urban community decided in 1998 to acquire a capacity for independent expertise on these complex issues by creating the Joint syndicate for the study and management of water resources in the Gironde department (SMEGREG). At the same time, these two territorial actors demand theinstallation of a local water commission (CLE) for the development of a water development and management plan for the deep aquifers of Gironde, SAGE which will be approved in 2003.

Today, the metropolisby its scale and its ability to cooperate with a wider scope of local authorities on the subjects of land management, demography, energy transition and climate change, plays a structuring role in local policies. This is what she claims from 2017 by promoting the idea of ​​”cooperative metropolis” within the framework of the cooperation protocols signed with the neighboring departmental capitals. But more locally, cooperation around water is the subject of tensions in terms of city/countryside representations and governance observation of urban projects and strategies (POPSU), The cooperative metropolis and its resources).

The department still remains today an essential actor in the strategic orientations in terms of water.. Indeed, it asserts its role as a developer and protector of biodiversity, which gives it a place of choice in supporting the good management of the resource. With the support of the Water Agencies, it accompanies small communities, medium-sized towns, rural intermunicipalities to finance investments. Many actors, including metropolitan ones, consider the need for management on a departmental scale, without the department appearing as the appropriate body.

This governance seems to be taking shape and being embodied, however, in the SMEGREG, recognized by the State in 2015 as a public territorial basin establishment for the deep aquifers of Gironde. It appears to be a key player in the management and sharing of the resource between territories. Financed and governed by the metropolis, the department and peri-metropolitan unions, its role as an expert on the question of deep aquifers is put to use in inter-territorial mediation on water as a common good. Its range of action, its objective scientific nature and its mode of operation, which place it equidistant from the various interests, make it possible to consider the resource on a territorial scale. A more cross-cutting governance is thus outlined and ensures an increase in the skills of actors who have hitherto been rather on the sidelines of these technical issues (town planners, elected officials, citizens).

The Landes du Médoc catchment field project

Faced with the finding of overexploitation of certain resources that supply the territory with drinking water, the CLE adopts in the SAGE deep aquifers a strategy to return to equilibrium, which is based on resource substitutions and on a priority policy of savings of water and control of consumption. The effectiveness of this policy has made it possible to accommodate 300,000 additional inhabitants in 20 years without increasing withdrawals for drinking water from the natural environment. In terms of substitution, the first structuring project being implemented is that of the catchment area (territory grouping works for the collection of underground drinking water in the same aquifer) of the Landes du Médoc, led by Bordeaux Métropole, which should be put into service in 2029 after 30 years of studies, 10 years of consultations and negotiations.

From the deliberation of the community council in 2013, the project sparked a conflict between its sponsors and local actors. (elected officials, associations and loggers). It provides for the construction of 14 remote boreholes at least of one kilometer from each other which will make it possible to distribute, in substitution for withdrawals from the Eocene (aquifers dating from -56 to -34 million years), 10 million cubic meters of water per year via a transport system (an adduction pipeline of approximately 30 km), to more than 900,000 Girondins, ie two thirds of the department’s population. All the Girondins benefit from the project directly, by receiving water from the Oligocene (from -34 to -23 million years), or indirectly by continuing to draw water from the Eocene. The main recipients of this water are metropolitan residents and 8 neighboring water associations. The overall cost of the operation amounts to nearly 100 million euros, co-financed by Bordeaux Métropole, the water agency, the Gironde department and the water unions.

The production, supply and sanitation of water require specific technical works and frameworks of thought that go beyond the administrative perimeters of the municipalities.. These projects encourage actors to dialogue to pool a resource, equipment, skills and aiming for an economy of scale, particularly in terms of network performance. Interconnections of drinking water networks between municipalities and drinking water unions have existed for a long time in order to carry out wholesale sales, repairs, to secure a water supply in the event of pollution or crisis. In recent years, however, an intensification of cooperation between metropolitan and peripheral territories applies in several areas (waste, food, health, air, water). The “concept of interterritoriality”, mobilized by the geographer Martin Vanier, therefore describes the increasingly inclusive functioning of territories vis-à-vis a resource in tension with high stakes.

The particularities of water management in a metropolis: Bordeaux or the “cooperative metropolis”