Indicator water

Nutrients in watercourses

Nitrate and phosphate in watercourses are good indicators of water pollution by nutrients which is anthropogenic, i.e. caused by human activity. Nutrients enter the water through municipal wastewater or discharge from intensively fertilised agricultural land. A higher nitrate or phosphate concentration does not normally have negative effects in a watercourse, but high phosphate discharges into standing waters can cause eutrophication. Nutrients also pollute the seas into which the rivers flow.

Assessment of the state
medium medium
Assessment of the trend
unsatisfactory unsatisfactory
poor 2019: 1.66666666666667 unsatisfactory 2019: 3.33333333333333 fair 2019: 17.5 good 2019: 46.6666666666667 very good 2019: 30.8333333333333 poor 2018: 3.2258064516129 unsatisfactory 2018: 7.25806451612903 fair 2018: 8.87096774193548 good 2018: 42.741935483871 very good 2018: 37.9032258064516 poor 2017: 0 unsatisfactory 2017: 4.42477876106195 fair 2017: 11.5044247787611 good 2017: 42.4778761061947 very good 2017: 41.5929203539823 poor 2016: 0 unsatisfactory 2016: 1.8018018018018 fair 2016: 9.90990990990991 good 2016: 45.045045045045 very good 2016: 43.2432432432432 poor 2015: 0.900900900900901 unsatisfactory 2015: 2.7027027027027 fair 2015: 9.00900900900901 good 2015: 41.4414414414414 very good 2015: 45.945945945946 poor 2014: 0.900900900900901 unsatisfactory 2014: 1.8018018018018 fair 2014: 2.7027027027027 good 2014: 53.1531531531532 very good 2014: 41.4414414414414 poor 2013: 0.900900900900901 unsatisfactory 2013: 0 fair 2013: 7.20720720720721 good 2013: 50.4504504504504 very good 2013: 41.4414414414414 poor 2012: 0.900900900900901 unsatisfactory 2012: 0.900900900900901 fair 2012: 10.8108108108108 good 2012: 45.045045045045 very good 2012: 42.3423423423423 poor 2011: 1.8018018018018 unsatisfactory 2011: 2.7027027027027 fair 2011: 8.10810810810811 good 2011: 46.8468468468468 very good 2011: 40.5405405405405
Assessment distribution of the 111, resp. since 2018 of the 114 NAWA monitoring stations for the parameter "Nitrate".

Data for the graph: Excel
Source: FOEN
poor Assessment: 12.5 unsatisfactory Assessment: 6.66666666666667 fair Assessment: 15 good Assessment: 17.5 very good Assessment: 48.3333333333333 poor 2018: 13.7096774193548 unsatisfactory 2018: 4.83870967741935 fair 2018: 9.67741935483871 good 2018: 20.1612903225806 very good 2018: 51.6129032258064 poor 2017: 9.73451327433628 unsatisfactory 2017: 7.07964601769912 fair 2017: 11.5044247787611 good 2017: 20.353982300885 very good 2017: 51.3274336283186 poor 2016: 8.10810810810811 unsatisfactory 2016: 6.30630630630631 fair 2016: 11.7117117117117 good 2016: 22.5225225225225 very good 2016: 51.3513513513513 poor 2015: 10.8108108108108 unsatisfactory 2015: 9.00900900900901 fair 2015: 13.5135135135135 good 2015: 21.6216216216216 very good 2015: 45.045045045045 poor 2014: 8.10810810810811 unsatisfactory 2014: 7.20720720720721 fair 2014: 11.7117117117117 good 2014: 20.7207207207207 very good 2014: 52.2522522522522 poor 2013: 6.30630630630631 unsatisfactory 2013: 7.20720720720721 fair 2013: 9.90990990990991 good 2013: 27.9279279279279 very good 2013: 48.6486486486487 poor 2012: 10.8108108108108 unsatisfactory 2012: 5.40540540540541 fair 2012: 16.2162162162162 good 2012: 22.5225225225225 very good 2012: 45.045045045045 poor 2011: 18.9189189189189 unsatisfactory 2011: 4.5045045045045 fair 2011: 12.6126126126126 good 2011: 21.6216216216216 very good 2011: 42.3423423423423
Assessment distribution of the 111, resp. since 2018 of the 114 NAWA monitoring stations for the parameter "Phosphate".

Data for the graph: Excel
Source: FOEN
Comment

78% of monitoring stations for nitrate and 66% for phosphate are in good or very good condition. Targets are however being exceeded locally in agricultural and developed regions (see map). Problems occur mainly in small streams with a high wastewater content or a high proportion of intensive farming in the catchment. These small watercourses are covered by the NAWA monitoring network.

The fluctuations between years are due to normal fluctuations in the runoff conditions rather than to a change in the pollution situation. As no significant improvement is observed between 2011 and 2019, the evolution of nutrients in watercourses is considered unsatisfactory.

Nevertheless long term time series do indicate that in general water pollution by nutrients has fallen significantly in the last few decades. The reduction in phosphorus content was particularly evident following the ban on phosphates in detergents in 1986. The phosphorus content continued to fall after 1990 due to the progressive expansion of wastewater treatment plants. Efforts in agriculture to reduce diffuse nitrate and phosphorus discharges, e.g. by less nutrient-intensive soil management and WWTP optimisation can contribute to a further reduction in nutrient concentrations in the water.

Method

The water quality is recorded jointly by the federal government and the cantons under the NAWA National Surface Water Quality Monitoring at approximately 120 monitoring stations. The chemical state of the water is evaluated on the basis of the phosphate and nitrate concentration by the method “Physico-chemical surveys, nutrients” in the modular stepwise procedure.

Basis for assessment of the trend
Targeted trend Initial value Final value Variation in % Observed trend Assessment
Growth Average 2011-2013 Average 2017-2019 -9.17% Decrease negative
Basis: very good, good
 
Last updated on: 22.07.2020

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