River basin
Water pollution in the Danube basin
- Sites in the 2025 yearbook
- 20
- Failed the standard (95%)
- 19
- Counted in the score
- 19
River basin overview
In the Danube basin the SHMÚ yearbook has 20 monitoring sites; in 2025, 19 of them (95%) failed the standard for at least one indicator. 19 are counted in the scores of the fishing districts.
Watercourse profile of Danube
SHMÚ sites from source to mouth
Watercourse profile from source to mouthnumber of unmet indicators in 2025 at SHMÚ sites
Show sites in the table (16)
- Hainburgriver km 1,878.93 indicators
- Bratislava, left bank, Nový mostriver km 1,869.01 indicator
- Bratislava, middle, Nový mostriver km 1,869.03 indicators
- Bratislava, right bank, Nový mostriver km 1,869.02 indicators
- WWTP Slovnaft, belowriver km 1,863.0no unmet standard
- Čuňovo Danubianariver km 1,851.61 indicator
- Rajkariver km 1,848.02 indicators
- Medveďovriver km 1,806.33 indicators
- Komárno, bridgeriver km 1,770.52 indicators
- Štúrovoriver km 1,718.8no unmet standard
- Szob, ferry left bankriver km 1,707.02 indicators
- Szob, ferry middleriver km 1,707.03 indicators
- Szob, ferry right bankriver km 1,707.01 indicator
- Impoundment I. Kalinkovo (left side)river km 15.02 indicators
- Červený Kláštorriver km 8.82 indicators
- Impoundment II. Šamorín (left side)river km 8.02 indicators
- standard not met
- no unmet standard
- site not in the yearbook
Year-by-year trend
Share of sites in the river basin that failed the standard
- 202214 of 2070%
- 202314 of 1878%
- 202412 of 1486%
- 202519 of 2095%
Fishing district map
Fishing districts in the “Danube river basin” by nearest SHMÚ site
Detailed filtersregion, district, riverbed, depth, shading, satellites, water chemistry and pollution, fish, geology
Move the map with two fingers. In full-screen mode one finger is enough.
The color of the fishing district line shows the number of indicators that failed the standard at the nearest SHMÚ site (2025). Gray fishing districts have no site with the same watercourse name nearby. You can also switch the color to groundwater and treatment plants.
Worst sites in the river basin
Click to expand the history by year
Chotínsky kanál, above the WWTP of MarcelováChotínsky kanál, river km 2.37 indicators in 2025
Indicator2022202320242025Oxygen and organic matterBOD₅ (biochemical oxygen demand)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metCOD (chemical oxygen demand)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metNutrients and nitrogenammonium–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not mettotal nitrogen–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not mettotal phosphorus–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metHarmful organic substancesAOX (adsorbable organic halogens)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metSalts, pH and mineralsdissolved solids, ignited (550 °C)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metThe location of the site is only approximate (based on the water body).
Chotínsky kanál, below the WWTP of MarcelováChotínsky kanál, river km 2.17 indicators in 2025
Indicator2022202320242025Oxygen and organic matterBOD₅ (biochemical oxygen demand)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metCOD (chemical oxygen demand)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metNutrients and nitrogenammonium–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not mettotal nitrogen–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not mettotal phosphorus–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metHarmful organic substancesAOX (adsorbable organic halogens)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metSalts, pH and mineralsdissolved solids, ignited (550 °C)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metThe location of the site is only approximate (based on the water body).
Hurbanovský kanál, below the WWTP of the town of HurbanovoHurbanovský kanál, river km 13.45 indicators in 2025
Indicator2022202320242025Oxygen and organic matterCOD (chemical oxygen demand)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metNutrients and nitrogenammonium–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not mettotal nitrogen–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not mettotal phosphorus–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metHarmful organic substancesAOX (adsorbable organic halogens)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metThe location of the site is only approximate (based on the water body).
Szob, ferry left bankDanube, river km 1,707.02 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites·standard met·standard met●standard not met●standard not metHarmful organic substancesAOX (adsorbable organic halogens)·standard met·standard met●standard not met●standard not metPAHs: 2 substances (not counted in the score)
Indicator2022202320242025PAHs (combustion and deposition)benzo(a)pyrene●standard not met·standard met●standard not met·standard metfluoranthene●standard not met·standard met·standard met·standard metPolycyclic aromatic hydrocarbons. The standard for benzo(a)pyrene is extremely low (0.17 ng/l), so most streams exceed it; the main sources are combustion and atmospheric deposition.
Nearest site for the fishing districts: Dunaj č. 1
HainburgDanube, river km 1,878.93 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites●standard not met·standard met●standard not met●standard not metHarmful organic substancesPFOS (perfluorooctane sulfonate)·standard met·standard met·standard met●standard not metSalts, pH and mineralsaluminium●standard not met●standard not met●standard not met·standard metPAHs: 1 substance (not counted in the score)
Indicator2022202320242025PAHs (combustion and deposition)benzo(a)pyrene●standard not met●standard not met●standard not met●standard not metPolycyclic aromatic hydrocarbons. The standard for benzo(a)pyrene is extremely low (0.17 ng/l), so most streams exceed it; the main sources are combustion and atmospheric deposition.
The location of the site is only approximate (based on the water body).
Bratislava, right bank, Nový mostDanube, river km 1,869.02 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites●standard not met·standard met●standard not met●standard not metHarmful organic substancesAOX (adsorbable organic halogens)·standard met·standard met·standard met●standard not metSalts, pH and mineralspH·standard met●standard not met·standard met·standard metPAHs: 1 substance (not counted in the score)
Indicator2022202320242025PAHs (combustion and deposition)benzo(a)pyrene·standard met●standard not met·standard met·standard metPolycyclic aromatic hydrocarbons. The standard for benzo(a)pyrene is extremely low (0.17 ng/l), so most streams exceed it; the main sources are combustion and atmospheric deposition.
The location of the site is only approximate (based on the water body).
Komárno, bridgeDanube, river km 1,770.52 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites·standard met·standard met●standard not met·standard metHarmful organic substancesAOX (adsorbable organic halogens)·standard met●standard not met●standard not met●standard not metSalts, pH and mineralspH●standard not met●standard not met●standard not met●standard not metBiology and bacteriaculturable microorganisms (22 °C)●standard not met●standard not met●standard not met·standard metNearest site for the fishing districts: Dunaj č. 2, Dunaj č. 2 – OR spodná inundácia
RajkaDanube, river km 1,848.02 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites·standard met·standard met●standard not met●standard not metHarmful organic substancesAOX (adsorbable organic halogens)·standard met·standard met·standard met●standard not metNearest site for the fishing districts: Dunaj č. 3 – OR horná inundácia
The location of the site is only approximate (based on the water body).
Bratislava, left bank, Nový mostDanube, river km 1,869.01 indicator in 2025
Indicator2022202320242025Nutrients and nitrogennitrites·standard met·standard met●standard not met●standard not metHarmful organic substancesAOX (adsorbable organic halogens)·standard met·standard met●standard not met·standard metSalts, pH and mineralspH·standard met●standard not met·standard met·standard metThe location of the site is only approximate (based on the water body).
Szob, ferry right bankDanube, river km 1,707.01 indicator in 2025
Indicator2022202320242025Nutrients and nitrogennitrites·standard met·standard met●standard not met·standard metHarmful organic substancesAOX (adsorbable organic halogens)·standard met·standard met●standard not met●standard not metBratislava, middle, Nový mostDanube, river km 1,869.03 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites●standard not met·standard met●standard not met●standard not metSalts, pH and mineralspH●standard not met●standard not met●standard not met·standard metaluminium●standard not met·standard met●standard not met·standard metBiology and bacteriaculturable microorganisms (22 °C)·standard met●standard not met●standard not met●standard not metPAHs: 1 substance (not counted in the score)
Indicator2022202320242025PAHs (combustion and deposition)benzo(a)pyrene●standard not met●standard not met●standard not met●standard not metPolycyclic aromatic hydrocarbons. The standard for benzo(a)pyrene is extremely low (0.17 ng/l), so most streams exceed it; the main sources are combustion and atmospheric deposition.
The location of the site is only approximate (based on the water body).
MedveďovDanube, river km 1,806.33 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites●standard not met·standard met●standard not met·standard metHarmful organic substancesAOX (adsorbable organic halogens)·standard met·standard met·standard met●standard not metSalts, pH and mineralspH●standard not met●standard not met●standard not met·standard metaluminium●standard not met●standard not met·standard met·standard metBiology and bacteriaculturable microorganisms (22 °C)●standard not met●standard not met●standard not met●standard not metPAHs: 1 substance (not counted in the score)
Indicator2022202320242025PAHs (combustion and deposition)benzo(a)pyrene·standard met·standard met·standard met●standard not metPolycyclic aromatic hydrocarbons. The standard for benzo(a)pyrene is extremely low (0.17 ng/l), so most streams exceed it; the main sources are combustion and atmospheric deposition.
Nearest site for the fishing districts: Dunaj č. 3 – OR stredná inundácia
The location of the site is only approximate (based on the water body).
Hurbanovský kanál, above the WWTP of the town of HurbanovoHurbanovský kanál, river km 14.63 indicators in 2025
Indicator2022202320242025Nutrients and nitrogentotal nitrogen–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metHarmful organic substancesAOX (adsorbable organic halogens)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metSalts, pH and mineralsdissolved solids (105 °C)–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metThe location of the site is only approximate (based on the water body).
State borderMošonské Rameno, river km 0.01 indicator in 2025
Indicator2022202320242025Nutrients and nitrogennitrites·standard met·standard met●standard not met●standard not metSalts, pH and mineralspH●standard not met●standard not met●standard not met·standard metaluminium●standard not met·standard met●standard not met·standard metBiology and bacteriaculturable microorganisms (22 °C)·standard met●standard not met·standard met·standard metHamuliakovoľavý priesakový kanál, river km 11.54 indicators in 2023
Indicator2022202320242025Nutrients and nitrogennitrites●standard not met●standard not met–site not in the yearbook–site not in the yearbookHarmful organic substancesAOX (adsorbable organic halogens)·standard met●standard not met–site not in the yearbook–site not in the yearbookSalts, pH and mineralspH·standard met●standard not met–site not in the yearbook–site not in the yearbookBiology and bacteriaculturable microorganisms (22 °C)●standard not met●standard not met–site not in the yearbook–site not in the yearbookThe location of the site is only approximate (based on the water body).
Krátke KesyChotínsky kanál, river km 2.13 indicators in 2023
Indicator2022202320242025Nutrients and nitrogenammonium–site not in the yearbook●standard not met–site not in the yearbook–site not in the yearbooktotal nitrogen–site not in the yearbook●standard not met–site not in the yearbook–site not in the yearbooktotal phosphorus–site not in the yearbook●standard not met–site not in the yearbook–site not in the yearbookSzob, ferry middleDanube, river km 1,707.03 indicators in 2025
Indicator2022202320242025Harmful organic substancesAOX (adsorbable organic halogens)·standard met·standard met·standard met●standard not metBiology and bacteriaculturable microorganisms (22 °C)·standard met●standard not met●standard not met·standard metchlorophyll a·standard met·standard met·standard met●standard not metthermotolerant coliform bacteria·standard met·standard met●standard not met·standard metintestinal enterococci·standard met·standard met●standard not met·standard metPAHs: 2 substances (not counted in the score)
Indicator2022202320242025PAHs (combustion and deposition)benzo(a)pyrene●standard not met·standard met●standard not met●standard not metfluoranthene·standard met·standard met●standard not met·standard metPolycyclic aromatic hydrocarbons. The standard for benzo(a)pyrene is extremely low (0.17 ng/l), so most streams exceed it; the main sources are combustion and atmospheric deposition.
Impoundment I. Kalinkovo (left side)Danube, river km 15.02 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metSalts, pH and mineralspH–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metNearest site for the fishing districts: Štrkovisko Kalinkovo
The location of the site is only approximate (based on the water body).
Impoundment II. Šamorín (left side)Danube, river km 8.02 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metSalts, pH and mineralspH–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metThe location of the site is only approximate (based on the water body).
Biskupické rameno, startBiskupické rameno, river km 4.51 indicator in 2025
Indicator2022202320242025Oxygen and organic matterdissolved oxygen–site not in the yearbook–site not in the yearbook–site not in the yearbook●standard not metThe location of the site is only approximate (based on the water body).
- standard not met
- no unmet standard
- site not in the yearbook
Fishing districts near these sites
Fishing districts whose nearest SHMÚ site lies in this river basin
- Ižianský kanál č. 1site Iža · standard not met in 1 of 4 years · nitrates in the groundwater nearby 0.5 mg/l4 indicators
- Ižianský kanál č. 2site Iža · standard not met in 1 of 4 years · nitrates in the groundwater nearby 0.5 mg/l4 indicators
- Dunaj č. 3 – OR stredná inundáciasite Medveďov · standard not met in 4 of 4 years · nitrates in the groundwater nearby 0.5 mg/l3 indicators
- Dunaj č. 2site Komárno, bridge · standard not met in 4 of 4 years · nitrates in the groundwater nearby 0.5 mg/l2 indicators
- Dunaj č. 2 – OR spodná inundáciasite Komárno, bridge · standard not met in 4 of 4 years · nitrates in the groundwater nearby 0.5 mg/l2 indicators
- Dunaj č. 1site Szob, ferry left bank · standard not met in 3 of 4 years · nitrates in the groundwater nearby 40.3 mg/l2 indicators
- Dunaj č. 3 – OR horná inundáciasite Rajka · standard not met in 2 of 4 years · nitrates in the groundwater nearby 2.7 mg/l2 indicators
- Štrkovisko Kalinkovosite Impoundment I. Kalinkovo (left side) · standard not met in 1 of 4 years · nitrates in the groundwater nearby 3.0 mg/l2 indicators
- Vydricasite Lafranconi · standard not met in 1 of 4 years · nitrates in the groundwater nearby 16.9 mg/lno unmet standard
- Dunaj č. 3site WWTP Slovnaft, below · standard not met in 0 of 4 years · nitrates in the groundwater nearby 0.5 mg/lno unmet standard
- Dunaj č. 3 – CHROsite WWTP Slovnaft, below · standard not met in 0 of 4 years · nitrates in the groundwater nearby 7.3 mg/lno unmet standard
- Dunaj č. 3 – Rusovecko – Jarovecká sústava ramiensite WWTP Slovnaft, below · standard not met in 0 of 4 years · nitrates in the groundwater nearby 6.9 mg/lno unmet standard
- Dunaj č. 4site WWTP Slovnaft, below · standard not met in 0 of 4 years · nitrates in the groundwater nearby 7.2 mg/lno unmet standard
What most often fails
Number of sites in the river basin that failed this indicator in 2025
- counted in the fishing district score
- shown, not counted in the score
Where the data come from and what they do not say
- Surface waters: yearbooks of the Slovak Hydrometeorological Institute (SHMÚ) Surface Water Quality for the years 2022 to 2025. We transcribed the list of sites and indicators that failed the standard under Government Regulation no. 269/2010 Coll. into a table in the plugin. Older yearbooks are in a different format and we did not include them.
- Groundwater: SHMÚ yearbooks Groundwater Quality, stations and indicators exceeded in 2017 to 2025 according to the drinking-water limits. The connection to the fishing district is only indirect.
- Groundwater, measured values: the public SHMÚ interface "Groundwater quality monitoring results". We have actually measured values (nitrates, ammonium, iron, chlorides, metals, pesticides, PFAS, solvents) for 758 stations; for each substance we take the highest value from the samples in 2025 (for stations without data for that year, from one of the two previous years). A value equal to the standard counts as an exceedance, as it does at SHMÚ.
- Treatment plants: register of wastewater treatment plants (VÚVH, EEA) from the "Points near fishing districts" file, that is, only plants within 2 km of the fishing district line. There are considerably more treatment plants in Slovakia.
What this data does not say. The yearbook lists the sites that failed the standard. A site missing from it is not proof of clean water, so the score of a fishing district is only ever lowered and never raised. We did not include industrial polluters (the National Pollution Register) in the list because the register was unavailable when the data was collected, and for wastewater treatment plants we list only those we found near the fishing districts. Only 31% of SHMÚ sites have an exact location, 47% have only an approximate location (based on the water body, so they count less near the districts) and 22% have no location at all, so we do not assign them to any district. We determine the distance, the match of the watercourse name and the ranking ourselves; the assignment is indicative.