The present paper study the wastewaters quality resulted from an ecologic storage yard in Prahova. To achieve the proposed goal, that of obtaining treated water, with parameters within the limits of Directive 91/271/EEC UWWTD for discharges in sensitive waters, the storage yard's wastewater treatment plant was monitored for a period of 6 months. The paper presents the time variation of the wastewater's quality indicators at both entrance and exit from the plant. The next 16 quality indicators of wastewater was studied at entrance and exit of wastewater treatment station: pH, suspension substances, biochemical use of oxygen at 5 days (CBO5), NH4+ , NO3- , NO2- etc; the analyses was weekly for 3 months. Also, the activated sludge's quality, from the biological phase, has been monitored.