Detailed characterization of measures, their effects and costs

As described in the analysis of pressures and impacts, there is an increasing trend in nitrate concentration in groundwater for the Krško polje aquifer. As a result, nitrate concentrations will soon reach the 37,5 mg/l of nitrate for action specified in the WFD. With the current nitrate load to the aquifer, it is expected that nitrate concentration in groundwater will reach an equilibrium value of 60 mg/l by 2018 (thus significantly higher than the drinking water standard of 50 mg/l) if no action is taken.

Different types of measures were envisaged, focusing in priority on the agriculture and household (wastewater collection and treatment) sectors as main contributors to pollution to the aquifer. The main measures identified through discussions with local experts and stakeholders are listed below, information on costs, coverage and effectiveness being summarised in Table 1:

• Establishment of Water Protection Area I (or WPA I) – This measure applies to the first level of water protection areas (Water Protection Areas I or WPAI, defined with a transportation time of water to the abstraction well of less than 50 days) already defined in existing legislation for the abstraction wells of Brege and Drnovo. The measure requires the abandonment of mineral fertiliser and use of organic fertilisation restricted to compost. The costs of this measure represent the end of farm production in arable fields and the installation of (quasi-natural) meadows.

• Establishment of WPA II & III - In other water protection areas (second and third circles of the Brege and Drnovo abstraction wells), it is anticipated to reduce fertiliser input from 188 kg/ha to 170 kg/ha (in line with the requirements of Good Managament Practices). The main costs of the measure are costs of extension for raising awareness for balanced nutrient input, support to rural economies, education, development of efficient monitoring and obligatory preparation of fertilization plans.

• Good Farming Practices - Measures corresponding to good farming practice consider the upgrading of manure pits, a decrease of input use to required standard for light soil and vulnerable area, the prohibition of fertilization during critical time periods of the year, efficient control of carrying out fertilization and other measures. The main costs of the measure are costs of extension for raising awareness for balanced nutrient input, support to rural economies, education, development of efficient monitoring and obligatory preparation of fertilization plans.

• Winter green cover – This measure aims at growing winter crops to capture remaining nitrates and limit leaching during the winter. Costs include the direct costs of farm practices to put winter green cover in place (ploughing, sowing, etc), but potentially also indirect costs that might result from changes in cropping pattern and other farm practices that are required because of the installation of green cover.

• Buffer zones – Buffer zones are grass or forest areas installed along water courses (5 m wide on each side) for limiting runoff and nitrate leaching to mainly surface water.

The cost of the measure is the related reduction in farm profit results from the abandonment of production for the areas under buffer zones. Although it is mainly implemented for surface water quality improvements, it can influence to a limited extend the quality of underground water.

• Ecological farming - Ecological farming implies that mineral fertilisers and chemical products are not used anymore and replaced by alternatives techniques and farm practices that are ecological. Today, there are around 5 to 10% of total farms involved in ecological farming in the area. It is expected that up to 15% of the farms could shift to ecological farming in the Krsko Kotlina area.

• Establishment of stricter WPA II & III for Brege – This measure is proposed for the water protection areas II & III linked to the Brege abstraction well. With this measure, fertilization should be prohibited, leading to a reduction in nitrate surplus from approximately 110 kg/ha to less than 5 kg/ha. The cost of the measure represents the loss in farm production resulting from the drastic reduction in fertilisation.

• Establishment of stricter WPAII & III for Drnovo – This measure is similar to the previous measure but it applies to the abstraction well of Drnovo. The cost of the measure represents the loss in farm production resulting from the drastic reduction in fertilisation. With this measure, fertilization should be prohibited, leading to a reduction in nitrate surplus from approximately 110 kg/ha to less than 5 kg/ha. The cost of the measure represents the loss in farm production resulting from the drastic reduction in fertilisation.

• Installation of septic tanks - Septic tanks have three treatment stages and they need regular sludge transportation to waste water treatment plants. It is estimated that this measure can be implemented for 25% of the population of the area, thus for 7 646 Population Equivalents (PE).

• Construction of small wastewater treatment plans for groups of individual houses (lower than 50 PE) - The measure foresees the installation of small waste water treatment plants with secondary treatment for individual houses or group of houses.

• Wastewater treatment plans for agglomerations between 50 and 2 000 PE. The measure foresees the construction of wastewater treatment plants for small settlements. It is assumed that the outflows from the waste water treatment plants will flow to surface waters and that 1% loss only will go to groundwater (leakage of sewage network).

• Renovation of existing sewage networks. Old networks might record high leakage rates that might have localised damaging impacts if close to abstraction points. The measure foresees the construction of wastewater treatment plants for small settlements. It is assumed that leakages to the aquifer will be reduced from around 10% to around 1%.

Table 1. Coverage, cost and effectiveness information for potential measures considered in the Krska kotlina groundwater case study (source: Krka Pilot

6. Status of measures 7. Unitary reduction in nitrates

Supplementary – Similar costs as for measure 1 but 15% higher because

land 0,0082731 mg/l/ha 1 582 534 SIT/ha 0,0052 10 8 WPA II, III –

additional Drnovo 0 ha 50 ha 50 ha 0,128 mg/l

Supplementary – Similar costs as for measure 2 but 15% higher because

land