ESTIMATION OF POLLUTANT LOAD IN DRINKING WATER PROTECTION AREAS OF SPRINGS SV. IVAN, BULAŽ, AND GRADOLE

In this paper, the estimation of pollutant load within the drinking water protection areas (DWPA) of springs Sv. Ivan, Bulaž, and Gradole in Northern Istria (Croatia) is presented. To estimate the pollution load, the spreadsheet tool for estimating pollutant load (STEPL) model was used. STEPL calculates loads of organic pollutants, nutrients, and suspended solids. For each analyzed spring total, specific and pollutant loads by each analyzed category are calculated. The results show that the greatest loads are caused by human activities. In addition, for the purpose of the analysis, two additional future scenarios are introduced; one describes the situation after the implementation of the first phase of the Istrian water protection system project, and the other that describes a possible future state where each agglomeration of over 100 inhabitants within the protected areas has an adequate wastewater treatment plant (WWTP).