USE OF WATER QUALITY INDICES AS A TOOL IN WATER RESOURCES MANAGEMENT

The purpose of this study was to analyze the use of water quality indicators (WQIs) in assessing water quality in four river basins closed by impacts with retention reservoirs constructed on these inlets, and evaluation the application of this tool in water resource management. Water samples for determination of physicochemical parameters were collected from inflows supplying water to the reservoirs, from the reservoirs from the layers near the surface and close to the bottom. Analyses also comprised samples of treated municipal wastewater reaching two of the studies rivers at points upstream the reservoirs, and samples of waters before their inflow to the reservoirs. Values of Water Quality Indicators were derived from 16 physicochemical parameters measured in 2004-2013. These numerous data, by means of the calculation method developed by the Canadian Council of Ministers of the Environment, were brought to single WQI values. Of key importance for the protection of water quality in rivers is the water and wastewater management carried out in river catchments. The input of treated wastewater to rivers is responsible for deterioration of the water quality class. This negative effect can be eliminated if water reservoirs are constructed below a wastewater treatment plant. Studies have shown their positive influence on the quality of water passing through such facilities, for example the CCME-WQI can rise by over 10 per cent. In consequence, the quality of water in rivers below such water bodies reached the same level as above a given WTP.