The Quality of Water Resources in Dalmatia

The purpose of this study was to monitor and record the specific characteristics and properties of most of the important water resources in Dalmatia located in Southern Croatia for a period of 5 years (1998–2002) according to established standards for drinking water. The paper presents a detailed account of their chemical content, the classification and the concentration of salts. The bacteriological pollution levels are indicated by the total coliform bacterial levels (MPN coli/100 mL). The water characteristics are expressed by coefficients, which represent the ratios between water ingredients. The Ca/Mg eq ratio, SO₄/Cl eq ratio and K₁, K₂ for bicarbonate hardness were calculated. The hygienic characteristics of the water samples were expressed by the total coliform bacteria estimation (MPN coli/100 mL), the permanganate consumption (KMnO₄) and biological oxygen demand (BOD₅). Karst waters in Dalmatia are moderately hard, the SO₄/Cl ratio is 0.38–1.6, non-corrosive (K₁ lower than 0.2) and not significantly mineralised (< 500 mg/L minerals). Sulphate waters are generally hard, the SO₄/Cl ratio is higher than 1.6, K₁ is 0.2–0.65. Marine waters are quite hard or hard, particularly at the river estuaries, the SO₄/Cl ratio is lower than 0.38, and K₁ is higher than 0.65. The groundwater and springs in Dalmatia are less polluted than surface waters. A majority of these have a geometric average value of MPN coli < 150/100 mL of water observed in 24 of 42 locations studied. The highest bacteriological pollution was found in nine locations where MPN coli > 1000/100 mL and moderate pollution was found in nine locations where MPN coli is between 150 and 1000/100 mL of water. The physical and chemical parameters determined for the most sources in Dalmatia are safe below the international permissible limits.