Intended for agricultural irrigation, it is at the heart of a battle for access to water in the Marais poitevin.

It is the second launched in a project of 16 substitution reserves, developed by a group of 400 farmers united in the Coop de l’eau, to “reduce withdrawals by 70%” in summer. Supported by the state, it would cost at least 60 million euros, 70% financed by public subsidies.

“Without watering, we will not last long,” fears Ludovic Vassaux, operator in organic polyculture-breeding and direct sales in Épannes, in the west of the department.

After irrigation restrictions from the spring and then an “unseen” summer drought, the 43-year-old farmer lost 30% of his production (mainly lentils, sunflower, wheat, alfalfa).

This holder of a BTS environment, who thought of converting himself as a professor of biology in order to have “a guaranteed salary”, is now waiting to be connected to a reserve to ensure a minimum income.

– “Grabbing”

These open-air craters, covered with a huge plastic tarpaulin, pump water from surface groundwater in winter to store up to 650,000 m3 (i.e. 260 Olympic swimming pools), before returning it for irrigation l summer, when rainfall is scarce.

According to the only scientific report available, published by the Bureau of Geological and Mining Research (BRGM), the project could, compared to the period 2000-2011, increase “by 5% to 6%” the flow of rivers summer, against a drop of 1% in winter.

This modeling, “exclusively quantitative”, does not take into account the potential evaporation of future reserves, nor the threat of recurrent droughts linked to climate change, specifies the regional management of BRGM to AFP.

The collective “Bassines Non Merci”, which brings together around fifty environmental associations, trade unions and anti-capitalist groups, denounces on the other hand a “grabbing of water” intended for “agro-industry”.

On October 29 and 30, these opponents plan to “converge by the thousands” to “end” the Sainte-Soline site and prevent a “general drainage” of the country, according to their spokesman Julien Le Guet.

Undeclared at this stage, this gathering remains closely monitored by local authorities.

Since 2020, previous demonstrations supported by LFI, EELV, the CGT, or the LPO, sometimes interspersed with incidents, have brought together up to 5,000 people in the plains of Mauzé-le-Mignon where the first restraint operates today.

Between the 1970s and 2000, in this area with many meadows flooded in winter, due to the groundwater buried just a few meters away, the marsh was drained to evacuate the water towards the sea and make plots accessible to tractors and suitable for cultivation. in corn, recounts Vincent Bretagnolle, agro-ecology specialist at the CNRS in Chizé (Deux-Sèvres) and member of the scientific and technical monitoring committee (CST) of the project.

For hydrogeologist Alain Dupuy, another member of the CST, “reserves alone will not be enough” to reverse this “imbalance” of the “great water cycle”. But in this very specific territory, “where aquifers and rivers are intertwined, interconnected”, “take water in abundance in winter and prohibit any withdrawal in the middle in summer should benefit wetlands, peat bogs and marshes” .

– “Leak forward” or “transition” –

Benoit Jaumet, local representative of the Confédération paysanne, denounces on the other hand “a headlong rush” of the productivist agricultural model.

The breeder, threatened in the past on social networks for this opposition, fears “an escalation in the water war” and defends “other levers” – agro-ecology, change of cultures, return of the meadows – before to build “smaller” reserves.

His union, a minority, supports the next rally to demand a “moratorium” but “does not call for actions of disobedience”, after degradations during previous demonstrations which notably affected Mr. Vassaux’s irrigation equipment.

Other market gardeners, members of the Water Coop but not connected to future reserves, fear that they will dry up their boreholes and devalue their land for the benefit of connected farms.

“These large basins are made for cereal farmers who produce corn and send it mainly abroad. Our small volumes do not interest them”, estimates Olivier Drouineau who cultivates 4.5 hectares organically near Mauzé- sur-le-Mignon.

According to the Regional Chamber of Agriculture, which supports the project, “85% of the maize produced” in the area primarily supplies farms in the Great West and its irrigated area has been divided by three since the 2000s.

For Thierry Boudaud, president of the Coop de l’eau and member of the FNSEA, giving up reserves “which secure water” would, on the contrary, favor large farms, better equipped and rotations – wheat, rapeseed, sunflower – less water greedy.

This farmer installed on 50 hectares, part of which is organic, qualifies these new works, “which will belong to the cooperative, not to the farms”, of “ecological transition accelerator” allowing to ensure the survival of “generations of farmers “.

– Engagements – 

After years of consultation between farmers, elected officials, authorities and associations, a protocol approved at the end of 2018 conditions access to water to changes in practices: reduction of pesticides by half, planting of a hundred kilometers of hedges and conversion to agro-ecology in the following five years.

This “ambitious” system will be controlled by automatic meters and state services will regularly visit each farm, with a reduction in water quotas for bad students, assures the prefecture of Deux-Sèvres. A positive point for Alain Dupuy, “favorable” to the project “if everyone plays the game” to “slow down the water cycle”.

But out of ten farmers using the first deduction, “none has subscribed to a reduction in pesticides”, notes Mr. Bretagnolle who warns against the situation in Spain, where “we have relied exclusively on the deductions and maintained a system water-intensive agriculture”.

Since the signing, several associations have withdrawn from the protocol.

In neighboring Vendée, the construction of 25 similar reservoirs since 2006 “has made it possible to significantly raise the level of the water table” but without preventing the frequent exceeding of alert thresholds, noted the Loire-Bretagne Water Agency in a 2021 study.