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Environmental information systems
Nutrients in European freshwater
Chart (interactive)
The figure shows the development in nitrate concentrations in European groundwater bodies and rivers, phosphate concentration in European rivers and total phosphorus concentration in European lakes.
The data series are calculated as the weighted average of country time series, using water body size (length for river water bodies, area for lake and groundwater bodies) per country as weights. The country time series are averages of gap-filled water body time series from each country.
Upper charts: Total oxidised nitrogen (nitrate + nitrite) is used where nitrate data is missing. Nitrite concentrations are usually very low, so total oxidised nitrogen and nitrate are considered comparable.
Assessment
Data sources
Metadata
More info
- WISE WFD Reference Spatial Datasets reported under Water Framework Directive 2022, European Environment Agency (EEA)
- WISE EIONET Spatial Datasets, European Environment Agency (EEA)
- WISE WFD Reference Spatial Datasets reported under Water Framework Directive, European Environment Agency (EEA)
- WISE Statistics, European Environment Agency (EEA)
- Waterbase - Water Quality ICM, European Environment Agency (EEA)
- Cyprus
- Portugal
- Spain
- Malta
- Denmark
- Iceland
- Switzerland
- Sweden
- Netherlands
- Austria
- Belgium
- Germany
- Luxembourg
- Ireland
- Türkiye
- France
- Liechtenstein
- Slovakia
- Czechia
- Norway
- Italy
- Slovenia
- Montenegro
- Croatia
- Bosnia and Herzegovina
- Greece
- Estonia
- Latvia
- Lithuania
- Serbia
- Finland
- North Macedonia
- Hungary
- Bulgaria
- Albania
- Poland
- Romania
- Kosovo (UNSCR 1244/99)
1992-2023
Units
Nitrate in groundwater: Milligrams of NO3 per litre (mgNO3/l)
Nitrate in rivers: Milligrams of NO3-N per litre (mgNO3-N/l)
Phosphate in rivers: Milligrams of PO4-P per litre (mgPO4-P/l)
Total phosphorus concentration in lakes: Milligrams of P per litre (mgP/l)
Additional information
Two time series are shown – a longer time series representing fewer water bodies and a shorter time series representing more water bodies. The shaded area indicates the confidence interval of the weighted mean.
Nitrate in groundwater:
The number of groundwater bodies included per country is given in parenthesis:
1992-2023: Europe (662), Austria (23), Belgium (26), Bulgaria (24), Denmark (6), Estonia (19), Finland** (9), France (319), Germany (167), Ireland (63), Slovenia (6).
2007-2023: Europe (2166), Austria (17), Belgium (52), Bulgaria (65), Cyprus (22), Czechia (157), Denmark (8), Estonia (21), Finland** (27), France (522), Germany (413), Ireland (95), Italy (176), Latvia (14), Lithuania (17), Netherlands (15), Poland (47), Portugal (72), Romania (25), Serbia (23), Slovakia (73), Slovenia (6), Spain (226), Sweden (34), Switzerland (39) (* = all data total oxidised nitrogen, ** = some data total oxidised nitrogen).
Nitrate in rivers:
The number of river water bodies included per country is given in parenthesis:
1992-2023: Europe (1398), Austria (53), Belgium (29), Czechia (59), Denmark* (36), Estonia (43), Finland** (68), France (236), Germany (133), Ireland** (15), Latvia (32), Lithuania (46), Norway (61), Poland (107), Slovakia (38), Slovenia (16), Spain** (307), Sweden* (113), Switzerland (6).
2007-2023: Europe (4936), Austria (63), Belgium (81), Croatia (21), Cyprus (21), Czechia (139), Denmark* (37), Estonia (50), Finland** (97), France** (1395), Germany (234), Ireland** (173), Italy (608), Kosovo*** (27), Latvia (20), Lithuania (54), Norway (59), Poland (80), Portugal (83), Romania (93), Serbia (32), Slovakia (35), Slovenia (17), Spain** (1300), Sweden* (124), Switzerland (93).
(* = all data total oxidised nitrogen, ** = some data total oxidised nitrogen, *** = Kosovo (under UNSC Resolution 1244/99).
Phosphate in rivers:
The number of river water bodies included per country is given in parenthesis:
1992-2023: Europe (1058), Austria (43), Belgium (33), Bulgaria (41), Czechia (37), Denmark (36), Estonia (44), Finland (68), France (221), Ireland (15), Latvia (33), Lithuania (44), Norway (28), Poland (89), Slovakia (20), Spain (191), Sweden (113), Switzerland (6).
2007-2023: Europe (4312), Austria (63), Belgium (81), Bulgaria (68), Croatia (21), Cyprus (21), Czechia (51), Denmark (37), Estonia (50), Finland (95),France (1395), Ireland (173), Italy (466), Latvia (20), Lithuania (54), Netherlands (51), Norway (54), Portugal (4), Romania (93), Serbia (34), Slovakia (34), Spain (1232), Sweden (122), Switzerland (93).
Total phosphorus in lakes:
The number of lake water bodies included per country is given in parenthesis:
1992-2023: Europe (402), Austria (5), Denmark (14), Estonia (9), Finland (177), Germany (10), Ireland (20), Latvia (5), Lithuania (4), Netherlands (7), Norway (61), Slovenia (2), Sweden (88).
2007-2023: Europe (921), Austria (28), Bulgaria (13), Croatia (8), Cyprus (9), Denmark (17), Estonia (10), Finland (162), France (13), Germany (14), Ireland (72), Italy (35), Latvia (7), Lithuania (5), Netherlands (69), Norway (70), Poland (22), Portugal (30), Romania (15), Slovenia (11), Spain (208), Sweden (103).
Methodology
The indicator analysis is based on annual mean nutrient per monitoring site. The annual mean concentrations are calculated from sample data, unless the country has reported annual data only. The data undergo automatic and manual quality checks to remove errors and outliers.
Monitoring site time series from the same water body are combined and gap filled before further analysis. Gap filling is necessary to ensure that the average European time series represents the same water bodies every year. Water body time series are only included in the analysis if they have data within the first and last five years of the time range and data from at least 40% of the years in the time range. Two different time ranges are analysed: From 1992 for long-term trends and from 2007 for better spatial coverage (more water bodies meet the selection criteria).
Data are aggregated from site to water body level and gap-filled using generalized additive models (GAM) in the free software R, using the mgcv package. For water bodies with more than one site, a GAM model with concentration as response variable, year as fixed effect and site as random effect is used to estimate annual concentrations per site. Annual values for the water body are subsequently estimated by averaging the annual site predictions. For water bodies with only one site, or where the random effect for site is non-significant, a GAM without a random site effect is used to estimate annual values and for gap filling. The gap-filled water body time series are averaged by country and a weighted average of the country time series (weighting by the total length of rivers or total area of lakes/groundwater in the country) is calculated to give the time series for Europe. A 95% confidence interval for the weighted average is calculated using of the formula for standard error of a weighted mean recommended in Gatz and Smith (1995).
