engleski

Endangered groundwater quality of the Strmec well field

Water supply of the City of Zagreb is based on pumping groundwater from the Quaternary aquifer on which the city had been built. Such a situation is a source of true conflict between the city and its water supply sector. The project Recording of data and economy of groundwater resources of Croatia (EGPV) has detected continual degradation of the groundwater quality. Further, the well fields have not been protected pursuant to the law. Inadequate enforcement of legislation resulted in apparent implementation of applicable protective measures, while such impression is completely false. The Strmec well field is the one of the main well fields for the water supply of Zagreb. It supplies with water the west part of Zagreb and Samobor. It is situated in the west part of Zagreb, on the right bank of the Sava River. The main groundwater pollution sources are Trebež waste disposal site which is located upstream of the well field, the open sewage system of Samobor, and the Rakovica creek. Additional polluters include agricultural lands, industrial facilities, illegal gravel pits and illegal waste dumping in abandoned gravel pits. Although the well field sanitary protection zones have been determined, the legal requirements of the governing Code are not easily enforced. Due to marginal conditions of the aquifer, its hydrogeological characteristics and numerous pollution sources, the quality of water is seriously imperilled. High concentration of iron and manganese, total and mineral oils, as well as heavy metals have been recorded in the groundwater. The paper shows their spatial and temporal variations during the last few years. The performed research has enabled an evaluation of impact of individual pollutants on water quality, using these data as the basis for prioritization of their remediation. Since a trend has been noticed of reduction in some chemical parameters in water, steps should be undertaken to see to its continuance in the future. If this does not happen, the water will have to be treated in order to obtain the quality requested by the regulations applying to the potable water.

Degradation of groundwater quality; polluters; Zagreb aquifer system

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