This demonstration project, developed in the Trancão river basin, integrated an eco-toxicological and psychochemical study of wastewaters from industries in different sectors, wastewater treatment plants as well as receiving waters. Project results can contribute to an EU legislative framework more in tune with Member State needs as regards management, control and improvement of wastewaters discharges quality. Some main conclusions and recommendations are: - DTA methodologies are available and should be used in evaluating and controlling complex wastewater eco-toxicity. - Following eco-toxicological assays of wastewaters, the use of a selected test battery with bacterium, algae and crustacean is proposed. - The eco-toxicological approach is clearly of added value in the hazard and risk assessment of discharges into receiving waters and can contribute to more correct establishment of discharge conditions. This would enhance protection of aquatic life and the good ecological status of receiving waters. - Modelling was demonstrated to be a useful tool to evaluate the impact of effluents on the receiving waters. Modelling also evaluated suggested management actions, identified risk areas and seasonal critical periods. Its use is recommended in monitoring programs of receiving waters and in the definition of toxicity limits for discharges based on discharged flow and dilution capacity. - The ecological characterization of receiving systems will benefit from sediment studies with chemical, eco-toxicological and biological components.