Meetings between local politicians, especially from the left, and citizens critical of the reservoirs also took place. These events were reported in the regional press and social networks [3]. An environmentalist media outlet, Reporterre magazine, published an article in December 2017, in which it talked about the battle between 226 pro-basins farmers, gathered in the Coopérative de l'eau des Deux-Sèvres, and anti-basins defenders of the Marais Poitevin (Poitevin Marshes) [1]. The article also specified that the water in the reservoirs would be taken from underground aquifers and rivers, and that, for the opponents, the amount of water that would be taken (15 million cubic meters per year) would be much greater than the current amount (between 8 and 10 million), and would lead to imbalances in the hydric system. Farmers, for their part, complained that they had had to economize on water in recent years, and that this had forced them to limit their production considerably [1].

On 11 January, 2018, an informational meeting was organized by BNM in Niort, followed on January 27 by a café-debate in the municipality of Melle. In the national press, meanwhile, an article in January raised the alarm about the unusually low level of two-thirds of French groundwater [4]. More activists’ initiatives followed, also including crowdfunding to finance a legal action to annul the prefectural decision on the authorization of the reservoirs [5]. Slowly, the range of basin opponents also expanded: in April 2018 BNM gathered the support from the Federation 17 of Fisheries [3]. Prominent among the most participated actions were the 4 March, 2018 demonstration in Mauzé-sur-le Mignon, which reassembled 2,200 citizens [6]; the June 3, 2018 demonstration in La Garette, attended by 1,500 people [7]; and the November 11, 2018 à Niort, attended by 1,200 people [8]. In these demonstrations of the BNM collective, the figure of Julien Le

Guet emerged, who in the following years was to be the focus of secret

surveillance operations by the French police [13].

Meanwhile, on November 20, a memorandum of understanding between farmers and environmental associations (but not including BNM) was concluded for the construction of 16, no longer 19 reservoirs [9]. In June 2019, another demonstration gathered over 700 protesters, while a month later a skirmish between pro-basin irrigators and anti-basin activists took place, with a farmer's tractor ramming two of the activists' cars [10]. On 11 October, 2020, in the midst of the Covid-19 pandemic, the BNM collective organized a large demonstration in Épannes, where the first construction site was scheduled to be built: more than 3,000 people participated [10]. At this point, also as a consequence of the restrictions imposed by the pandemic, protest activity came to a standstill, until 22 September, 2021 in Niort, when a demonstration launched by BNM and the Les Soulèvements de la Terre (The Earth Rising) movement, attended by about 700 people, penetrated the construction site of the Mauzé-sur-le-Mignon reservoir and occupied it for two hours [11]. Hundreds of farmers participated in the protest [12].

In October, activists were made the target of police surveillance and restraint actions [13]. In November, the situation became more tense, during another demonstration of nearly 3,000 anti-basin militants near Niort, organized by BNM, Soulèvements, and the farmers’ trade union Confédération paysanne, on 6 November. During the protest, activists broke into the Mauzé-sur-le-Mignon town hall to unfurl a banner against the basins, while the Cram-Chaban basin in the Charente-Maritime county was damaged. Clashes with police also took place [14]. In their discourses, members of the collectives denounced the hoarding of water by intensive farmers; the disruption of the water cycle; the consequences on biodiversity; the public financing of the works without having warned the population; the repercussions on water quality; and the disregard of European directives and the opinion of the administrative court, since the prefectural decision authorizing the construction of six basins—including the damaged one—had been annulled by the courts already in late 2009 [15][16]. In March 2022, surveillance devices, installed by the police, were found at the usual gathering places of anti-basin activists [17]. On the 26th March, the largest anti-basin demonstration to date was organized, gathering nearly 7,000 people in La Rochénard, under a strong police surveillance device [18]. Clashes occurred between protesters and police, with fireworks and tear gas being thrown, respectively. During the demonstration, a pipe that could have been used to feed a future reservoir was dug up.

On May 17, activists score a victory. The Bordeaux administrative appeals court ruled that five docks in Cram-Chaban and the Mignon basin (Charente-Maritime) were illegal. The court thus annulled the prefectural decree that had authorized them, finding that the additional elements provided by the Authorized Syndicated Irrigation Association (ASAI) of the Roches were insufficient to ensure that these basins had a limited impact on the environment [16]. In early October, 40 membership organizations, unions, NGOs called on the citizenry to participate in the October 29-30 demonstration for the end of the construction site at Sainte-Soline. 1,700 gendarmes and 7 helicopters were mobilized to guard the demonstration, which was attended by 7,000 people (according to the organizers, 4,000 according to the prefecture). The militants failed, as they had planned, to enter the site of the construction site, defended with tear gas and defense flash-ball guns by the police. By the end of the demonstration, there were 50 injured protesters, 5 of whom ended up in the hospital; 3 protesters injured by deafening grenades; 4 protesters arrested; 3 members of parliament and Julie Le Guet truncheoned. But on the 30th of October, some militants dissected some 20 meters of pipes connected to the Sainte-Soline construction site [19]. Opponents of the megabasins gave the government two weeks to stop the construction and announce a moratorium. Otherwise, they stated they would announce a new date for a demonstration. On 28 November, five activists arrested during the demonstration were sentenced to between two and three months in prison, suspended. They deserted the trial at the beginning of the hearing [20].

In January 2023, five people were convicted of acts of damage and violence against gendarmes, committed during the September 2021 demonstration [21]. In the same month, a black box is discovered under the axle of Le Guet's truck, which later police confirm they placed to geolocate the activist [22]. Meanwhile, the 'water war' expanded to the Ile-de France [23], where, in Banthelu, more than a hundred people assembled to demonstrate against plans to build megabasins. In late January, BNM published a counter-report criticizing the results of a BRGM (Bureau de recherche géologique et minière, France's public reference institution in Earth Science applications) study on reservoirs, commissioned by the Coopérative de l'eau. The BRGM study [24] claimed that the water withdrawals would be negligible for the water table, while the BNM study reopens the debate on the usefulness of the megabasins.

On 3 February, the Council of State confirmed the ban on farmers filling the five disputed basins in Charente-Maritime, upholding the decision of the Bordeaux Administrative Court of Appeal [25], but on 17 February a press release by the Coopérative de l'eau announced that the Mauzé-sur-le-Mignon basins had been completely filled [26]. Anti-basin militants organized a demonstration for March 24-26 in Sainte-Soline and Mauzé-sur-le-Mignon. While the Deux-Sèvres prefecture banned it, citing possible damage to the contested structures as the reason [27], the collectives announced they would stick to the agreed plan. On 17 March, Le Guet was detained in custody by the gendarmerie, then referred to the Niort prosecutor's office, which imposed a ban on him entering the territory of Sainte-Soline [28][29].

From 24 to 26 March 2023, the largest-ever anti-basins demonstration took place at Sainte-Soline. The three-day event brought together over 30,000 participants (according to the organizers), also including parlamentrians from the left-wing party LFI/NUPES. On 24th a tractor motorcade was organized; on 25th, violent clashes occurred between the protesters and the 3,200 police force sent to the field. Two police vans were burnt, while the police used tear gas, dispersal grenades, and flash-ball guns to disperse protesters [30] [31]. At the end of the event, the organizers counted 200 protesters wounded, while the police counted 47 injured in its ranks [32].

The reservoir in Mauzé-sur-le-Mignon (Deux-Sèvres) is planned to occupy 5 hectares, 300 meters wide, 150 long and about 10 meters deep. It can store 240,000 m3 of water. 70% of the project is to be funded by public grants [36].