The study of sludge accumulation in the first ponds of 12 treatment plants under oceanic climate showed a mean rate of accumulation of 2.8 cm per year corresponding to 0.12 m3 of sludge per inhabitant per year. Desludging was required about operation periods of 6 or 7 years. Sludge removal by pumping after or without emptying water is the most convenient and with a mean cost of 40FF per m3 the cheapest method. Mean desludging cost is eight times lower than mean investment cost. With regard to their agronomic characteristics stabilization pond sludges have a low fertilizer value because of their long maturation time.