The recent advances in current status and major mechanisms of water quality worsening, assessment of evaluation criteria and the influencing factors were reviewed. The changes in the atmosphere, the periodicity of the occurrence of extreme hydrological situations has been increasing in recent years. In the natural conditions of Slovakia, periods without rain are lengthening and the incidence of precipitation of extreme intensity and abundance is increasing. Hydrological extremes are generally manifested in the form of floods and droughts. The increased incidence of drought is a new phenomenon. The analysis was conducted using a long series pH and temperature measurements.
The pH, temperature and conductivity are the most important water quality parameters. Their time-series were used for investigation of pH with regard to the place of collection and seasonal cycle. The pH ranged from 5 to 9, i.e. predominantly in the alkaline area. Average value of pH in the monitored period 2010-2020 was 7.56, One of the most important tools for evaluating water quality and character in a catchment is a detailed knowledge of the ranges and trends in pollution of natural water. This requires water accounting be conducted at the regional scale.