Environmental quality of surface water and natural areas, 1990-2010

Improvement in environmental quality

Environmental quality and water quality have improved in natural areas since 1990. The environmental pressure from eutrophication, acidification, desiccation and poor water quality is decreasing. However, the environmental pressure is still too high to ensure an optimum quality of habitat for many species. The fact that sustainable conditions have not yet been achieved means that many threatened species continue to decline.

Decrease in acidification, but overfertilisation still a problem

National and international environmental policies have resulted in cleaner air and therefore lower acid and nitrogen depositions (Buijsman et al., 2010). Despite these improvements, air pollution is still too high for the sustainable conservation of many natural areas. Soil acidification is taking place much more slowly than it was, but is still happening. The main problem is currently nitrogen from acid rain, which has both an acidifying and a fertilizing effect, and is causing acute problems in nature. Depositions higher than the critical load are seen in many National Ecological Network (EHS) and Natura 2000 areas.

Improved fresh water and salt water quality

The water quality of fresh and salt water in the Netherlands is slowly improving, due to national and international policy. One large obstacle however is excessive nitrogen and phosphorus fertilizer use, as seen in the eutrophication of fresh surface waters. The thresholds are exceeded most for phosphorus in smaller water bodies such as lakes, ditches, canals and streams. The major rivers are almost on target. Half of the water bodies assessed in the Water Framework Directive (WFD) were considered to be of insufficient quality. The high concentrations are responsible for the poor ecological status of the water bodies, and the water quality is still too low to protect water-dependent biodiversity (van Puijenbroek et al., 2010).
The main obstacle in terms of environmental pressure on fresh waters is currently the high nitrogen concentrations. In 2011, this was twice the threshold value. Nitrogen concentrations have increased in the Wadden Sea and the North Sea since 2004, and concentrations in 2011 were the highest in the last ten years.

Desiccation a persistent obstacle and not monitored

Biodiversity conservation on land depends on suitable moisture levels. However, many natural areas are too dry, because of low groundwater levels and/or poor groundwater quality. Nature policy aims to improve this. According to a survey carried out by the Association of Provincial Authorities (IPO) and the Institute for Inland Water Management and Waste Water Treatment (RIZA) in 2004, 3% of the desiccated land has been fully hydrologically restored since 1990, and 13% partly restored. According to the provinces, about 222,000 hectares of natural areas in the EHS were desiccated in 2006. Of this, 70,000 hectares were Natura 2000 areas. This is the most recent survey of the status of desiccated areas, due to a lack of national monitoring data.