Located in Allonzier-la-Caille, the Mandallaz Marsh, a former peat bog managed by Asters-CEN74 since 2020, is the site of significant restoration efforts scheduled to conclude by the end of 2026. This wetland area has faced numerous disturbances, including drainage, planting, infilling, abandonment of agricultural practices, and subsequent overgrowth of the site.
The objective of these interventions is to restore the wetland's proper hydrological and ecological functioning. Actions undertaken by Asters-CEN74 include raising and re-meandering the Moulins stream, removing buried drains, excavating ponds, and topsoil stripping – a technique involving the removal of the superficial soil layer to restart the natural peat formation process.
These measures are deemed essential to restore the natural space's full potential for water resource preservation, carbon capture, and biodiversity conservation.
The work, which commenced on October 15, 2026, and will continue until late December 2026, is being carried out by companies SAEV and DUCLOS TP. Project management is handled by Asters, Conservatoire d'espaces naturels de Haute-Savoie (Asters-CEN74), with financial partners including the Rhône-Méditerranée-Corse Water Agency and CDC Biodiversité.
