GAVE DE PAU floodwaters (at 400-450 m³/s, with a 100-year flow rate of 650 m³/s) attacked the stream’s right bank over a 150-m length (30-m setback) and eroded a former public dumpsite left derelict since 1986. 10,000 to 20,000 tonnes of waste from 2 storage cells were carried by the current all the way to Lourdes. Local authorities called the Geological Surveying Office to help with erosion mitigation works. Since the GAVE DE PAU had engulfed the riverbed’s entire width, it was preferred not to constrain the watercourse by channelling flow into the former main arm. A solution aimed at closing off the active arm, which had formed with the levee built using on-site materials, was rejected due to an overly small rock material size distribution. It was then decided to erect an anti-erosion screen over a 200-m length along the block of wastes. This solution was quick to implement and did not modify the river flow path. The screen was composed of a pyramidal stacking of 600 one-m³ big bags (2 at the base, 1 on top) filled with materials found on-site or nearby. Such a solution, known to be unsustainable over the long run, would not replace a proper rehabilitation and retention programme.