River basin
Water pollution in the Tisza basin
- Sites in the 2025 yearbook
- 2
- Failed the standard (100%)
- 2
- Counted in the score
- 1
River basin overview
In the Tisza basin the SHMÚ yearbook has 2 monitoring sites; in 2025, 2 of them (100%) failed the standard for at least one indicator. 1 are counted in the scores of the fishing districts.
Watercourse profile of Tisza
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 (2)
- Malé Trakanyriver km 3.03 indicators
- Zemplénagardriver km 0.03 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
- 20222 of 2100%
- 20232 of 2100%
- 20242 of 2100%
- 20252 of 2100%
Worst sites in the river basin
Click to expand the history by year
Malé TrakanyTisza, river km 3.03 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites●standard not met●standard not met·standard met·standard metHarmful organic substancespetroleum substances (NEL)●standard not met·standard met●standard not met·standard metAOX (adsorbable organic halogens)●standard not met·standard met·standard met·standard metBiology and bacteriachlorophyll a●standard not met·standard met●standard not met●standard not metphytoplankton abundance●standard not met·standard met●standard not met·standard metsaprobic index of biosestone·standard met●standard not met●standard not met·standard metPAHs: 2 substances (not counted in the score)
Indicator2022202320242025PAHs (combustion and deposition)benzo(a)pyrene●standard not met●standard not met●standard not met●standard not metfluoranthene·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: Tisza
The location of the site is only approximate (based on the water body).
ZemplénagardTisza, river km 0.03 indicators in 2025
Indicator2022202320242025Nutrients and nitrogennitrites●standard not met●standard not met·standard met·standard metHarmful organic substancesAOX (adsorbable organic halogens)●standard not met·standard met●standard not met●standard not metBiology and bacteriacoliform bacteria●standard not met●standard not met●standard not met·standard metculturable microorganisms (22 °C)●standard not met●standard not met●standard not met·standard metintestinal enterococci●standard not met●standard not met●standard not met·standard metthermotolerant coliform bacteria·standard met●standard not met●standard not met·standard metphytoplankton abundance●standard not met·standard met·standard met·standard metchlorophyll a·standard met·standard met·standard 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.
The 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
- Tiszasite Malé Trakany · standard not met in 4 of 4 years3 indicators
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.