Joint perspectives

Interview with Tiphaine Hinault, Director of CPIE Logne et Grand-Lieu and Mathieu Goriaux, Research Engineer at the Water and Environment Laboratory (LEE), Université Gustave Eiffel.

Mathieu Goriaux : The two main challenges are water availability and quality. Due to global warming and long periods of drought, water restrictions set by prefectural decree are arriving earlier in the season. Machecoul-Saint-Même has not been spared from this phenomenon. The other issue that communes must face is pollution and a high number of water contaminants: phytosanitary products, pesticides, metals, per- and polyfluoroalkyl substances (PFAS/PFOA), etc.

Tiphaine Hinault : At CPIE, we are also interested in the storage and use of mains, well and rain water. It is very useful to study a town like Machecoul-Saint-Même, which is located at the edge of a large amount of farmland, as we do not have enough data about this kind of area.

M.G. : The scientific literature is concentrated on metropolitan and rural zones. Our study provides new insight in that it focuses on an intermediary zone, one that until this point has been little studied.

M. G. : On the topic of water management and storage, we identified lead contamination at a private individual’s home, which was due to roof renovations. It’s important to increase awareness among users about maintaining their rainwater collection systems (in particular, by draining it annually) and to remind them of the risks of water contamination when renovating. In terms of recommendations to manufacturers, we need to facilitate the installation and removal of collection systems, and also improve the closing mechanism.Another interesting point relates to the values of compounds measured: it turns out that well water is of better quality, on the whole. Compounds such as glyphosate, sulfosate, metolachlor and propyzamide were all detected in rainwater.

T. H. : This study made it possible to observe that there is no correlation between pesticide levels and agricultural areas, at least at the commune level. While it’s important to keep in mind that only a certain number of sample areas were analysed, this fact is worth highlighting. It challenges the link often made, blaming pesticide pollution solely on farming activity. The study also revealed another result: water use is not always what you’d expect. While typically, well water is used for the garden, some residents also use it in the kitchen and bathroom.

M.G. : We were short on time during the study. We have submitted a project to the ARS in the hope of continuing it, specifically, raising awareness by organising talks for the general public and distributing educational materials on the topic of water quality.