The dikes of the Bonfol ponds show local settlements and erosion. The drainage works are also in poor condition. The State, owner of the premises, is currently beginning major work which will continue until the end of the year. These interventions will increase safety in the event of flooding and promote the specific flora and fauna of this biotope of national importance.
The first historical mention of the presence of ponds in Bonfol dates back to the end of the 15th centuryth century. We take advantage of the marl subsoil to dig bodies of water, which are then exploited for fish farming. Since then, numerous redevelopments have modified the configuration of the site. Listed in the federal inventory of low marshes of national importance and the federal inventory of amphibian breeding sites of national importance, the places contain flora and fauna of great value, testifying to the exceptional character of the site. Anxious to maintain this wealth but also to strengthen the stability of the dikes and prevent the risk of flooding, the State will begin security work from next week.
At the Etang du Milieu, the body of water located at the entrance to the site, the summer weather of 2021 revealed weak points in the structure of the dikes. The work carried out by the State will therefore aim to raise the dike on the south bank in places where it has subsided. The leaks will be sealed with marl and the dike will be locally widened and reinforced with mesh. This last measure aims to prevent muskrats from digging their galleries in the dike and thus weakening its structure. A new outlet will be created and the installation of an overflow will make it possible to manage large flows during floods. Logging, limited to a minimum, will nevertheless be necessary for the needs of the site.
At the three ponds located to the north of the site and commonly called “Champs de Manche”, the regulating valves, currently corroded and dilapidated, will be replaced. The new systems that will be installed will allow finer regulation of water levels according to seasonal cycles and rainfall, which will be favorable to certain target species.
These interventions are carried out in coordination with the Etang Monnier Fishing Society, which partly ensures the maintenance of the site. Given the site’s inclusion in several federal inventories, this work will benefit from a subsidy from the Confederation. They will make it possible to perpetuate and improve the biological, fish farming and recreational uses of this centuries-old site of great natural and heritage value.
