Freshwater - State and impacts (Croatia)

Water quantities

The total quantity of water available in Croatia is approx. 156.32x10⁹ m³ per year, out of which 23% are own waters. Surface water quantities have been systematically monitored for many years, while determining of groundwater reserves is partly based on estimates due to complex hydrogeologic relations at the Croatian territory and insufficient and inconsistent aquifer prospecting (Table 1).

 Table 1. Quantities of surface inland water (water balance), 1961-1990

Source: Hrvatske Vode (Croatian Waters)/ Water Management Strategy 

Inland water quality

The quality of inland water is monitored and assessed in order to protect and preserve water quality in accordance with the Regulation [4]. The assessment of inland water quality in this report, prepared in accordance with the Regulation [1], does not include its amendments, since they were passed at the end of 2008. The number of stations at which the quality of inland water is monitored is given in Table 2.

Table 2. Number of stations for monitoring inland water quality in Croatia by basin districts, 2004-2008

Source: Hrvatske vode (Croatian Waters) 

According to their quality, inland waters are classified into one of five classes in relation to the allowed limit values of indicators of oxygen regime, nutrients, and microbiological and biological indicators, while excluding dissolved oxygen, oxygen saturation and nitrates as indicators of groundwater quality. Water classes are graphically presented by colour, namely blue for class 1, green for class 2, yellow for class 3, red for class 4 and black for class 5.

In the period 2004–2008, surface inland water mostly belong to class 2 with respect to biological parameters, class 2 and 3 with respect to oxygen regime and nutrients, and class 3 and 4 with respect to microbiological indicators (Figure 1). There is a characteristic trend of a slight decrease in BOD₅ and ammonia concentration in rivers and lakes, i.e. organic pollution of rivers and lakes as a result of construction of sewerage systems and commissioning of new urban wastewater treatment plants.

According to the limit values of indicators for metals, in the period 2004–2008, surface inland waters mostly belong to class 1 with respect to zinc and nickel content, and in 2007 and 2008 to class 1 with respect to cadmium content (Figure 2a, b, c). Other metals monitored in the water column (copper, chromium, lead, mercury) are below the detection thresholds of the methods used.

At the majority of monitoring stations, the quality of groundwater corresponds with class 1 (Figure 3). Deviations from the planned class of groundwater were mostly due to nutrients and microbiological indicators. Nitrate pollution in groundwater, which is monitored pursuant to the Ordinance [2] that stipulates the maximum allowed concentration (MAC) of nitrates in groundwater of 50 mg NO₃/L, varies by river basin (Figure 4). Settlements are mostly supplied with abstracted groundwater (90 % of the total quantities), and thus their protection is of special importance.