Zmiany jakości wód Odry w latach 1992-1997

Pollution levels were estimated by conventional methods made use of in Poland and by the criteria recommended in relevant EU directives. The results obtained using 'domestic' methods differred from those achieved in terms of tlwEU criteria. And this indicates that the erection of hydroengineering struc-tures (especially when they are to operate on transboundary waters) requires decisions made on an international level in order to specify which of the available methods forwater quality assessment must be used. Our analyses showed that, irrespective of the estimating method applied, the quality of the investigated riverine water improved continually, and the rate of quality variations differred according to the pollutant under analysis. When use was made of the EU criteria, a considerable portion of the total river length carried water which was fit for municipal supply — provided that the treatment train involved advanced processes. Our analyses also showed that organic matter con-centrations and salinity decreased at a faster rate than did nutrients.