Chemical status of surface waters

In 2015, almost 40 percent of Dutch surface waters met the standards for good chemical status according to the European Water Framework Directive. In 2009, this was still 70 percent. The decline was mainly caused by changes in the measurement programme and tightening of the standards. 

In 2015, standards were exceeded both for more substances and in more surface waters. The most disturbing chemical substances in this compliance check are tributyltin, brominated diphenyl ethers, mercury, nickel and some polycyclic aromatic hydrocarbons (PAHs).

 Full compliance with quality standards 1 substance exceeds standard2 substances exceed standard3-4 substances exceed standard5 or more substances exceed standardUnknown
200969.919.83.60.415.4
201537.624.915.611.15.94.9

Distribution of approximately 700 tested Dutch surface water bodies to the number of substances that exceed the quality standards according to the European Water Framework Directive. The compliance check was carried out for 33 selected substances. The next formal compliance check will be made for the year 2021.

The issue

The availability of sufficient fresh water resources of good quality is a basic prerequisite for humans and their economic activities. This works in two ways. Economic growth is only possible when sufficient reliable water resources are available. Conversely, economic growth must not lead to decreasing water quality and over-exploitation of water resources. The challenge in green growth is to find the right balance. Chemical pollution of surface water threatens the aquatic environment and can lead to acute and chronic toxicity to aquatic organisms, accumulation in the ecosystem, losses of habitats and biodiversity and threats to human health.

Analysis

Most chemical pollution of surface waters can be linked to human economic activity. A broad set of measures is aimed at reducing these emissions, even to zero. However, the effects of these measures are still not visible when tested, but the assessment is strict. A water body already fails to comply when even only one substance exceeds the standard ('one out, all out'). In total, 5 percent of all assessed measurements in Dutch water bodies do not comply with the standard. One of the substances with poor compliance is tributyltin. Tributyltin is used in anti-fouling paint for ships, and is now banned. Other substances with exceedences are polycyclic aromatic hydrocarbons (PAHs), mercury and nickel. The main source of PAHs and mercury is atmospheric deposition of air pollution and for nickel the run-off and leaching of agricultural and natural soils. In most water bodies where the chemical status is not satisfactory only one or two substances exceed the standards, but there are also thirty water bodies where five substances do not comply, and two water bodies with an exceedance for six substances (Environmental Data Compendium, 2018).