DEVELOPMENT OF LEAST-COST WATER-QUALITY CONTROL POLICIES FOR THE NITRA RIVER BASIN IN SLOVAKIA

The Nitra is one of the most polluted rivers in Slovakia due to numero us municipal and industrial discharges, as well as the low level of wa stewater treatment. The ongoing economic transition and lack of financ ial resources for water quality management calls for the development o f short-run least-cost policies on the basis of ambient standards or a combination of ambient and effluent ones. A water quality control pol icy model was developed which incorporates dissolved oxygen simulation models, alternative municipal treatment plans and dynamic programming . Least-cost policies to achieve various water quality goals were deve loped and compared to effluent standard based strategies (including th at deriving from the application of the ''best available technology'') . The role of industrial emissions was demonstrated in a sensitivity f ashion, while the influence of parameter uncertainty on the developed policies was analyzed in a multiobjective framework. The analyses show that significant cost savings are possible in comparison to uniform, effluent standard policies. They also suggest that a long-term strateg y should be realized on the basis of a sequence of properly phased lea st-cost policies corresponding to ambient standards to be tightened gr adually.