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Aggregate level assessment

Nitrate in groundwater

The average nitrate concentration in European groundwater is fluctuating around the same level and there is no clear trend (Figure 1). The shorter, but more representative time series starting in 2000 follows the longer one closely. Agricultural activities, such as over-use of fertilizer, is the main driver for nitrate in groundwater.

Nitrate in rivers

The average nitrate concentration in European rivers decreased steadily over the period 1992-2009 but has levelled off since then. The shorter time series is parallel to the longer series, but the concentration level is lower. Agriculture remains the main contributor to nitrogen pollution, but the EU Nitrates Directive and national measures have contributed to lower concentrations. However, the apparent stabilisation in recent years calls for further measures.

Phosphate in rivers

The average phosphate concentration in European rivers more than halved over the period 1992-2011. The marked decline is also evident for the shorter time series, but the average concentration is somewhat higher. From 2011 onwards the concentration tends to level off and in the last five years even increase, indicating a need for further measures. The overall decrease in river phosphate can be related to measures introduced by national and European legislation, e.g. the Urban Waste Water Treatment Directive. Also, the change to phosphate-free detergents has contributed to lower phosphate concentrations.

Total phosphorus in lakes

There has been a gradual reduction in average total phosphorus concentration in European lakes since 1992, but the concentration levels off from 2015. The concentration level is somewhat higher for the shorter, more representative time series. As the treatment of urban wastewater has improved, phosphorus from detergents has been reduced, and many wastewater outlets have been diverted away from lakes, so phosphorus from point sources has become less significant. However, diffuse runoff from agricultural land continues to be a major phosphorus source in European lakes. Moreover, phosphorus stored in sediment can keep lake concentrations high despite a reduction in inputs.