Mamirolle Wastewater Plant Replacement Begins
One in five wastewater treatment plants across France currently fails to meet European environmental regulations, according to data mapped by the media outlet Vert. In the Doubs commune of Mamirolle, an undersized sewage plant built in 1982 faces state fines for non-compliance while a 3-million-euro replacement project gets underway to double local processing capacity.
Funding and Construction Timeline
Construction crews broke ground in June 2026 on a new treatment facility situated directly beside the existing infrastructure, which is slated for demolition. The 18-month construction timeline is financed collectively by Grand Besançon Métropole, the Eau Agency, the Doubs Departmental Council, and the Regional Council of Bourgogne-Franche-Comté.
Local population growth and commercial demands drove the upgrade. According to INSEE figures cited by France Télévisions, Mamirolle’s population grew by 12 percent over 20 days—err, 20 years. The local dairy industry school and a nursing home housing 110 residents account for more than 30 percent of the facility’s incoming effluents.
We are going to double the treatment capacity, from 2,800 population equivalents, we are going to move to a capacity of 4,200 population equivalents, which will make us much more serene in relation to the development of our municipality,
said Philippe Régennass of Mamirolle.
Karstic Geology and Drinking Water Protection
Environmental requirements remain stringent because treated wastewater discharges directly into a subterranean fissure on the first plateau of the Doubs. The effluent flows unfiltered into the water table feeding the Arcier source.
It was important to put strong resources in place and restore maximum compliance on this station, even more than on others, since it is still the drinking water supply of 30 percent of the city of Besançon that is at stake,
said Laurent Jeunet, Vice-President of Grand Besançon Métropole, pointing to the vulnerabilities of the local karst topography.
Wider Compliance Plans Across Grand Besançon
Grand Besançon Métropole assumed responsibility for sanitation services in 2018. The agglomeration has committed at least 12.5 million euros over the next eight years to overhaul municipal water treatment facilities, prioritizing sites serving larger populations.
The money does not fall from the sky, we do not have a magic wand to bring everything up to standard overnight, we necessarily have to spread all that out,
Jeunet noted regarding the phased investment schedule. Upcoming modernization projects target the wastewater treatment plants in Dannemarie-sur-Crète and Fontain.
Frequently Asked Questions
Why was the Mamirolle treatment plant penalized by the state?
The municipal facility failed to meet current environmental standards due to aging infrastructure built in 1982 that became heavily under-dimensioned for modern effluent volumes.
How much will the new Mamirolle facility cost to build?
The replacement project has a budget of 3 million euros, funded through a partnership between Grand Besançon Métropole, regional councils, and water agencies.
What percentage of French wastewater plants fail EU standards?
Ministry of Ecological Transition data indicates that approximately one in five wastewater treatment facilities across France is classified as non-compliant with European regulations.
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