Quality of water

Criteria: chemistry and ecology

In the Water Framework Directive (WFD) standards have been set for different substances for each type of water body (drainage ditches, lakes, rivers, coastal water, ground water.)
Surface water quality is assessed in two ways. Firstly, it is assessed whether water is chemically healthy. That is to say, whether certain dangerous substances are found in the water (such as lead, cadmium and mercury) and, if so, in what concentrations. If the water is chemically healthy, it is said to be in 'a good condition chemically'. A body of water is given this appraisal if it remains within the standard limits set by the European Union (EU) for all substances. The standards are recorded in the Decree on Quality Standards and Monitoring for Water 2009 (in Dutch).
Then the ecological quality of the body of surface water is assessed. To what extent are there fish, algae, water plants and small animals present? The temperature of the water and the presence of nutrients and a number of chemical substances fall under this assessment. If the score remains within limits that have been harmonized within the European Union (EU), then the water body is said to be in an 'ecologically good condition'. The numerical values that are linked to the EU targets are recorded in the Water Framework Directive Monitoring Programme (in Dutch). There are quality standards that pertain to ground water as well. These standards are recorded in the Decree on Quality Standards and Monitoring for Water (2009, in Dutch).

Chemical situation in rivers, canals, lakes and drainage ditches

Of the four river basin regions named, the Rhine delta and the Scheldt score the best results. More than 80% of the surface water in these river basins has been given a ‘good’ score. The Ems (60%) and Meuse (25%) score significantly less well. Substances that regularly exceed the set maximum limits are: crop protection agents, PAHs, PCBs, copper, zinc and ammonium, cadmium and tributyltin. The primary sources of these pollutants are agriculture and industry.
Human and veterinary medicines form a separate problem. The remnants of medicines are secreted and thus increasingly are found in Dutch surface water. Drinking water is collected from this surface water (especially in the western part of the country). However, the amounts of medicine found are low and have a negligible effect on public health.

Ecological situation in rivers, canals, lakes and drainage ditches

In 2009 the objective was achieved almost nowhere. Roughly half of all rivers, drainage ditches and lakes have high concentrations of nitrogen and phosphates (a result of over-fertilisation in agricultural areas). In addition, the water in the river basin of the Rhine is too warm in some places due to cooling-water discharges by industry.
The presence of fish, small water animals, water plants and algae varies widely between the different water regions. The state of small water animals, in particular, is often moderate at best and in the large rivers even poor. Fish that want to swim between salt water and fresh water run into considerable obstacles such as dams and sluices. Here, too, the rule is: exceeding the limit one time means that a body of water can no longer lay claim to the qualification of 'good'.

Chemical situation of North Sea coast, Wadden Sea and the Ems-Dollard region

In the salt water and brackish water (mix of salt-fresh water) areas, the presence of nearly all substances remains below the maximum limits for pollution. Only the substance of tributyltin still forms a problem. Tributylin is a substance (now largely banned) that is painted below the waterline of ships’ hulls to retard the growth of algae and barnacles.

Ecological situation of North Sea coast, Wadden Sea and the Ems-Dollard region

The quality of the water plants in the salt water and brackish water areas is poorer than it is in fresh water. The concentrations of nitrogen are above the norm limits in all three areas. This is caused by the drainage of nitrogen (manure) from the land. An overabundance of nitrogen in the water can occasionally lead to an excessive growth of algae. The murkiness of the water also regularly exceeds the norm. Murky water is often a result of the dredging of the waterway.