Application of water quality indices to the assessment of the effect of geothermal water discharge on river water quality – case study from the Podhale region (Southern Poland)

Abstract

In the European Union the basic requirements in the subject of the appropriate quality of water, constituting a habitat for fish, was established in Directive 2006/44/EC (EU, 2006) on the quality of fresh waters needing protection or improvement in order to support fish life (currently implicitly repealed by Directive 2000/60/EC). This legislation presents the list of parameters that should be controlled together with their guide and mandatory levels, methods of analysis as well as minimum sampling and measuring frequency. Based on the case study from the Podhale region in southern Poland, the impact of used geothermal water discharge on river water quality was assessed, in particular in the context of the quality of the life of salmonid fish species. The variability of the chemical composition of river water as a result of used geothermal water discharge was assessed both in statistical terms and in correlation to river flows. To quantify the water quality in terms of protection of the fish life, a new Fish-Water Pollution Index was developed. In the presented case, similarly to the Water Quality Indices and Heavy Metal Pollution Indices, also the Fish Water Pollution Indices values calculated upstream and downstream of the used geothermal water discharge, do not display significant differences.