Looking ahead for groundwater research

During his presentation on 11 October at the National Regions Day, Van Loon set out an overview of results from the groundwater research that KWR has conducted for a variety of clients, including the Groundwater Quality Monitoring Network Managers’ Platform, provincial authorities, the sector research for water companies (BTO) and the Water Quality Knowledge Impulse. Following on from the National Regions Day, the groundwater researcher was a guest recently on the Dutch radio talk show Spraakmakers (NPO Radio 1), where he stated his concerns about the quality of groundwater in the Netherlands. “We are seeing how pollutants that have entered groundwater in recent decades are moving deeper and deeper. We are also finding more and more substances. In other words, groundwater is turning out to be slightly less clean than we had assumed for a long time. That means that our stocks of clean groundwater are steadily diminishing.”

Outline of the problems with groundwater quality

A brief outline: groundwater is, and will continue to be, an important source of drinking water production. As much as 60 percent of our drinking water comes from groundwater. But groundwater quality is under pressure as large numbers of pollutants reach greater and greater depths. Groundwater extraction for drinking water production is expected to run up against this greying process in groundwater in the decades ahead. Precise forecasts of trends in groundwater quality trends are not yet available. Van Loon: “Research is therefore needed into the properties of substances found in groundwater and how they compare to those we have already observed in extraction wells.” Obviously, we are not working in the dark in terms of groundwater quality. In 2020, the KWR report ‘Groundwater Quality in the Netherlands 2020’ was published, opening up the way to the visualisation of the problem of emerging pollutants. The report provides a national picture that provincial authorities can use to tighten up their monitoring programmes in order to meet the objectives.

Protect to stay

“Drinking water companies have already made some changes to their extraction strategies in light of the undesirable changes in groundwater quality,” says Van Loon. “In the past, extraction activities have been terminated or extraction wells deepened in several places to avoid pollutants. There are two reasons why drinking water companies are running up against the limits of what is possible. Given the undesirable impact on the environment, new or deeper extraction locations are almost impossible to find now. In addition, deeper groundwater is more susceptible to salinisation. So we will have to make do with the extraction locations we have now. We will need to protect the groundwater quality in these locations properly. And so ‘Protect to Stay’ is the new motto for groundwater protection policy.”

The greying of groundwater

Changes in the chemical quality of groundwater was the subject of a comprehensive report that was published as part of the Water Quality Knowledge Impulse. During his presentation at the National Regions Day, Van Loon gave a brief description of the causes of this contamination. “The greying of groundwater is the result of high historical loads since the industrial revolution and the later intensification of agriculture. Since the introduction of the Dutch fertiliser policy in the 1980s and the WFD in 2000, major steps have been made in the reduction of emissions. Even so, environmental policy has proved unable to stop contaminants entering groundwater. This is in part because standards for use and regulations for fertilisers and nitrates are not based on zero emissions; they allow the stacking of pollutants. The substitution of substances and the continuous production of new substances also play a role. The WFD status reports drafted by the Netherlands for groundwater bodies do not link up well with WFD objectives for sources used for drinking water. These reports do not flag failures to meet drinking water objectives and so the policy response needed to reduce the emissions of emerging substances is unnecessarily slow.”

Vision of the future

What steps are needed now to protect our groundwater? One might think that, with the WFD deadline (2027) approaching, the plans in this area are firmly in place. But that is not the case, knows Van Loon. “A range of government programmes have been introduced to comply with the objectives for reducing the nitrogen burden on nature and for drought management. But groundwater quality plays only a minor role in these programmes. So we need to look ahead: no pollutants should be allowed to enter groundwater that will result in damage later or that will have to be removed. This vision of the future is not based on emission reductions alone; it also emphasises that we need to use our natural capital – soil, groundwater and the subsurface – responsibly. Substances that will not affect other functions as they break down can, if specific conditions are met, continue to be used. In that case, for example, surface water will not necessarily pose a threat to groundwater quality after infiltration and it can actually help to clean up polluted groundwater. At the same time, stricter restrictions should apply to substances that pass easily into deeper groundwater. This will require a clearer understanding of the origin, spread and properties of pollutants, as well as the buffer capacity of the subsurface.”