KAZALCI OKOLJA
  1. Home
  2. Water
  3. Nitrates in groundwater

[VD05] Nitrates in groundwater
State

Key message
Neutral

Groundwater in intergranular aquifers in Slovenia is most affected by nitrate pollution, particularly in northeastern Slovenia. In contrast, groundwater in karst and fissured aquifers is less impacted due to geographical conditions, lower population density, and a smaller proportion of agricultural land.

For the period 2019–2024, poor chemical status was identified in the water bodies of the Savinja, Drava, and Mura basins. The main cause of poor chemical status in all water bodies was nitrate, with atrazine additionally contributing in the Drava basin.

In recent years, the number of monitoring sites where the annual average nitrate concentration exceeds the quality standard of 50 mg NO₃/L has been decreasing. Statistically significant downward trends in nitrate concentrations during the period 1998–2024 were observed in the Drava and Mura basin water bodies. In the Savinja basin water body, no statistically significant trend was detected over this period.

This indicator shows:

  • Average annual values ​​of nitrate in groundwater samples in Europe and Slovenia and at the sampling points of the Slovenian national monitoring in 2020.
  • Structure of agricultural land use and groundwater quality in the analzyed year.

  • Share of agricultural area in the surface of ground water bodies in Slovenia in the analyzed year.

  • Total annual nitrogen emissions from municipal wastewater treatment plants.

Charts

Figure VD05-1: Average nitrate values at groundwater monitoring sites in 2024
Sources:

ARSO, GURS (2025)

Figure VD05-2: The average value of nitrate levels in Europe and in Slovenia and Slovenian groundwater bodies with predominantly intergranular (alluvial) and karst/fractured aquifers
Sources:

Standardised Database for Water Quality Monitoring, Slovenian Environment Agency; Waterbase European Environment Agency (2025)

Show data
Slovenija - alluvial aquifers[mg/l] Slovenia - karst-fractured aquifers[mg/l] Slovenia - average[mg/l] Europa - average[mg/l]
2004 40.60 7.50 15.40 20.79
2005 40.30 7.40 15.20 20.86
2006 38.60 7.40 14.80 20.88
2007 31.80 7.30 13.10 21.27
2008 32.80 6.80 13 21.39
2009 32.90 6.60 12.80 21.10
2010 31.90 5.50 11.80 21.56
2011 31.20 6.60 12.50 20.72
2012 30.20 5.40 11.30 21.34
2013 32.30 5.30 11.70 21.22
2014 32.20 5.30 11.70 21.32
2015 31.10 5.80 11.80 21.35
2016 25.40 5.50 11.40 21.64
2017 31.70 5.90 12 21.06
2018 32 5.60 11.90 21.18
2019 30.10 5.80 11.60 20.82
2020 29.20 6.20 11.70 20.43
2021 31.60 5.80 12 20.59
2022 31 5.20 11.40 20.65
2023 30.70 5.10 11.20
2024 29.70 5.50 11.30
Figure VD05-3: Average annual nitrate levels in groundwater of the more polluted water bodies
Sources:

Standardised Database for Water Quality Monitoring, Slovenian Environment Agency (2025)

Show data
1001 Savska kotlina in Ljubljansko barje[mg/l] 1002 Savinjska kotlina[mg/l] 1003 Krška kotlina[mg/l] 3012 Dravska kotlina[mg/l] 4016 Murska kotlina[mg/l] quality standard[mg/l]
1998 23.40 50 21.80 45.10 47.60 50
1999 22.80 43.80 23.80 48.40 39.80 50
2000 21.60 47.20 20.40 45.40 47.30 50
2001 21.90 55.50 25.70 46.50 50
2002 20.70 43.90 33 39.70 34.40 50
2003 20.70 50.50 22.30 40.30 39.90 50
2004 20.90 65 29.40 49.50 38 50
2005 22.90 57.80 24.80 54 42 50
2006 22.70 45.40 26.90 53.30 44.70 50
2007 18.40 47.30 21.10 39.10 32.90 50
2008 19.60 48.70 23.20 40.30 32.20 50
2009 20.60 44.80 24.20 42.10 32.60 50
2010 19.20 42.50 24.10 42.20 31.80 50
2011 19.20 43.20 21.60 39 32.90 50
2012 18.20 46.90 23.70 35.60 26.70 50
2013 18.90 40.20 28.70 42.30 31.40 50
2014 18.80 44 24.50 40 33.70 50
2015 18 44.70 23.60 40.30 28.70 50
2016 16.70 42 24.50 38.50 30.30 50
2017 16.80 49.80 24.10 39.10 28.70 50
2018 18.80 44.40 25.70 39.70 31.20 50
2019 17.50 47.80 21.90 36.10 27.40 50
2020 16.10 46.10 19.90 35.30 28.70 50
2021 18.50 43.80 23.10 38.80 33.70 50
2022 17.10 46.80 21.80 38.70 30.40 50
2023 19.20 40.30 24.30 36.90 32.80 50
2024 19.30 38.80 24.30 35.10 31.10 50
Figure VD05-4: Kemijsko stanje, število merilnih mest in število merilnih mest s preseganjem nitrata na bolj obremenjenih aluvialnih vodnih telesih v obdobju 2017-2022
Sources:

Standardised Database for Water Quality Monitoring, Slovenian Environment Agency, (2025)

Note:

MM: Merilno mesto
 

Show data
Vodno telo podzemne vode Leto 2017 2018 2019 2020 2021 2022
1001 Savska kotlina in Ljubljansko barje Kemijsko stanje dobro dobro dobro dobro dobro dobro
  Št. MM 50 48 49 51 48 48
  Št. neustreznih MM 2 3 2 2 3 0
1002 Savinjska kotlina Kemijsko stanje slabo slabo slabo slabo slabo slabo
  Št. MM 13 13 12 13 13 13
  Št. neustreznih MM 6 3 6 6 5 6
1003 Krška kotlina Kemijsko stanje dobro dobro dobro dobro dobro dobro
  Št. MM 14 14 14 13 13 13
  Št. neustreznih MM 0 2 0 1 1 1
3012 Dravska kotlina Kemijsko stanje slabo slabo slabo slabo slabo slabo
  Št. MM 25 27 28 27 26 27
  Št. neustreznih MM 9 13 9 9 9 11
4016 Murska kotlina Kemijsko stanje slabo slabo slabo slabo slabo slabo
  Št. MM 13 13 13 13 13 13
  Št. neustreznih MM 2 2 2 2 3 2
Figure VD05-5: The declining trend of the nitrate concentration in water bodies Sava, Savinja, Mura, and Drava basin in the period 1998-2022
Sources:

Standardised Database for Water Quality Monitoring, Slovenian Environment Agency (2025)

Figure VD05-6: Total nitrogen emissions from municipal wastewater treatment plants (t / year)
Sources:

Waste Water Treatment Plants Database, Environmental Agency of the Republic of Slovenia (2025)

Show data
Indirect outflow into groundwater[t/year] Outflow into surface waters[t/year]
2010 5.90 1993.30
2011 6.60 2011.40
2012 3.40 1710.40
2013 2.40 1707.10
2014 4.50 1634
2015 5.90 1502
2016 9.70 1321.40
2017 9.90 1315.50
2018 12 1388.60
2019 12.80 1283.10
2020 10 1233.40
2021 12.50 1256.90
2022 12 1159.30
2023 11.30 1074.10

Goals

  • To improve the state of the water environment,
  • to reduce emissions from dispersed sources (intensive agriculture, dispersed settlement without wastewater treatment),
  • to achieve a favourable state of groundwater,
  • to reduce concentrations of nitrates in overburdened groundwater below 50 mg NO3/l and to reverse the trends of increasing nitrate concentrations.

 

Methodology

Last modified
05.09.2025
Author(s)

Polona Mihorko, Marina Gacin, Marjan Zajc, Agencija RS za okolje; Janez Sušin, Janez Bergant, Kmetijski inštitut Slovenije