Nutrient Pollutants in Surface Water—Assessing Trends in Drinking Water Resource Quality for a Regional City in Central Europe

This paper presents the changes in concentration of seven biogenic indices in the Wisłok River water and determines the water treatment processes required in order to obtain water fit for consumption. The investigations were conducted during 2004–2013, and water samples were collected at a measuring-control point was situated at 67.9 km on the river at the surface water intake for the water supply to the Rzeszów city dwellers. Analysis of the research results allows for the forecasting of technological and organizational changes in the treatment processes of the abstracted water. It was found that only the mean concentration of Kjeldahl nitrogen exceeded the value admissible for class I, which allowed the Wisłok River water to be classified as class II with good potential and determined the water quality category as A2, which indicates the necessity for typical performance physical and chemical treatment. Downward trends in the contents of the tested nutrients occurred during the period of investigation, except for nitrite nitrogen. Statistically significant downward trends were registered for ammonium nitrogen, Kjeldahl nitrogen, total nitrogen and phosphates. The decline in nutrient concentrations in the water of Wisłok is a tangible result of the introduction of new standards of water resource management in the catchment, compliant with the European Union legislation