17 questions about drought and low water levels in the Rhine and Meuse

How low are the low water levels measured in the Rhine and the Meuse in July?

On Wednesday 15 July 2026, the daily average flow of the Rhine at Lobith had fallen to 771 m³/s. This makes it the lowest flow ever recorded in July. The previous record dates from the ‘record drought year’ of 1976.

The daily average flow of the Rhine (Tuesday 4 August 2026) is now around 640 m³/s, and the Ministry of Infrastructure and Water Management, Rijkswaterstaat and the water boards have escalated the situation to the ‘Actual water shortage’ phase (colour code: orange).

The low water levels and reduced water inflow are having a wide range of consequences, and numerous measures are being taken to minimise the negative effects as much as possible. Most of these measures are intended to ensure our safety. For example, locks are being closed to prevent head losses from causing water levels in drainage basins and canals to fall further. This is because the reduction in water pressure associated with such low water levels can cause subsidence and instability in riverbanks and dykes.

Water loss through locks also causes relatively salty water to intrude into freshwater systems. This has negative consequences for nature, drinking water and other water uses. To ensure the prudent use of freshwater surface water and groundwater, withdrawal bans are also in force in some regions.

Why are water levels so low so early in the season?

There are a number of reasons for this:

1. A relatively dry spring: there was little rain to feed the river.
2. A relatively warm spring: the non-permanent snow melted earlier than usual. Evaporation was also higher than in other years.
3. Little inflow from glaciers, as much of it has melted away due to global warming.

Could it get worse? What does the predictions say?

Although temporary, modest increases in the Rhine’s flow are expected due to rainfall, the flow is also expected to drop again afterwards.

What are the consequences of low water levels for the public?

• We are being urged to use less drinking water.
• We are noticing effects on recreation: e.g. restrictions on recreational boating, blue-green algae, and swimming bans.
• Increased damage to foundations due to subsidence or uneven settlement resulting from peat and clay soils drying out

What are the consequences for the drinking water supply?

Persistent drought and low river flows can lead to restrictions on surface water abstraction due to salinisation, contamination or low water levels. During hot spells, demand for drinking water can also rise sharply, putting pressure on the security of supply.

However, following the most recent periods of drought, sufficient measures have been taken in the Netherlands to ensure that, in the short term, we need not worry about drinking water.

What are the potential consequences for nature?

Drought can lead to the drying up of streams, pools and nature reserves, with negative consequences for biodiversity and ecosystems. In the event of repeated or prolonged drought, some effects may be long-lasting or irreversible.

What are the potential consequences for the dykes?

Dykes in regions where the water level is consistently high, such as the drainage dykes in Friesland and North and South Holland, consist largely of clay or peat. As a result, they are highly sensitive to even small drops in water level. A drop of just ten centimetres can be enough to cause them to subside noticeably. This is an irreversible process. In the event of larger drops, the dyke may even become unstable. This is much less of an issue along watercourses where water levels have always fluctuated significantly, such as the major rivers.

What are the potential consequences for shipping?

Low river flows can limit the load capacity of ships, making transport more expensive and less efficient. Prolonged low water levels can cause disruptions to logistics chains and the supply of goods to businesses. Waiting times at locks, for example, become longer, as is the case at Terneuzen and IJmuiden. By using locks more sparingly, less salt water enters the waterways. Ultimately, waterways may also be closed.

What are the potential consequences for agriculture?

Drought can lead to an increased need for irrigation and, locally, to lower yields when there is insufficient fresh water available. The consequences vary greatly depending on the region, the crop and the ability to retain or supply water.

What is ‘salinisation’ and why is it particularly relevant at the moment?

Salinisation is the process by which salty seawater moves inland via surface water or groundwater. When river flows are low, salty seawater can penetrate further inland, reducing the amount of fresh water available for people, nature and agriculture. This can lead to restrictions on drinking water abstraction, as well as for agriculture and industry. In addition, additional measures are required in water management, and salinisation leads to a deterioration in water quality. Salinisation occurs in various locations, for example where there is an open connection to the sea, such as via the Nieuwe Waterweg. Due to low river flow, the salt penetrates further upstream, and measures are needed to ensure that water abstraction from the Hollandse IJssel and Lek remains as fresh as possible (including the Climate-Resilient Water Supply scheme). In addition, salt intrusion can also occur in canals and lakes: here, salt often enters the canal or lake via lock gates. Due to the drought, discharge is under pressure here too, which means that salinisation can build up slowly. In the North Sea Canal near IJmuiden, a ‘salt screen’ or ‘selective discharge’ system has now been constructed to specifically discharge the salt water back into the sea. As for groundwater salinisation, this can increase in deep polders due to water abstraction and low water levels in the canals and ditches. As there is little water available to flush the system, salinisation also increases here during periods of drought.

What are the consequences for the quality of our river water?

Low flows and high water temperatures can lead to higher concentrations of pollutants, algal blooms and oxygen depletion. This can have consequences for nature, drinking water production, recreation and industrial water users.

Will businesses still have access to sufficient water?

Low discharge rates may reduce the availability of process and cooling water and hamper the supply of raw materials. Industries that rely on inland waterway transport or surface water are the most vulnerable in this regard.

What does the future hold? Will this situation occur more frequently?

Yes, we see this reflected in all climate scenarios. Global warming is leading to increased evaporation, less snow, earlier snowmelt, reduced glacial meltwater and changing precipitation patterns, with less rainfall in summer. On balance, droughts and low water levels will occur more frequently and be more severe.

To what extent does climate change play a role?

Climate change is one of the main causes of the increasing likelihood of low water levels. Climate Scenarios for the Rhine Basin show that the river’s discharge regimes are changing. Higher temperatures lead to greater evaporation and less water storage in snow and glaciers. As a result, less water is discharged into the rivers during the summer. The consequences are exacerbated by the fact that demand for water actually rises during dry periods.

That is why Deltares looks not only at climate, but also at the interplay between climate, the economy, agriculture, energy supply, nature and water use. This is being investigated, amongst other things, within the European STARS4Water project under the EU Horizon research programme and the CHR studies for the Rhine catchment area.

Does future water use play a role in water availability?

Water availability concerns whether there is sufficient usable water available when people, nature and the economy need it. Low river flows are a key factor here, but water quality, salinisation and the scale of water demand also play a major role. Research shows that human water use influences the Rhine’s discharge: low discharge levels can fall even further due to consumption.

Agriculture and industry, in particular, can increase water demand upstream, whilst in the Netherlands, additional fresh water is needed to combat salinisation, land subsidence and water level problems. Climate change and rising water demand reinforce each other, meaning that temporary shortages may arise sooner.

Read about impact of changing water demand on the transboundary Rhine River basin

Technical or nature-based solutions we should be exploring

There is probably no silver bullet that will solve the problem of low water levels. The solution lies rather in a smart combination of measures spread across the entire river basin, from source to sea.

Examples of technical measures include optimising reservoir management, improving water distribution, increasing freshwater buffers and promoting more efficient water use by agriculture, industry and water supply companies. In addition, we are looking into ways of retaining water more effectively during wet periods.

Nature-based solutions are at least as important. These include the restoration of wetlands, stream valleys and floodplains, improving the sponge effect of landscapes, and increasing water storage capacity in nature reserves. Such measures can contribute to drought resilience, biodiversity and water quality simultaneously.

For Deltares, one insight is particularly important in this regard: the Rhine and Meuse are international systems that pay no heed to national borders. Effective solutions therefore require not only measures within the Netherlands, but also cooperation across the entire river basin.

Dependence on and cooperation with upstream countries

The Netherlands is, to a large extent, dependent on water entering the country via international river basins such as the Rhine and the Meuse. Cooperation with upstream countries is therefore essential.

Cooperation within and with river commissions

Countries in the Rhine and Meuse river basins have been cooperating for decades through international river commissions. For the Rhine, these include the International Commission for the Protection of the Rhine (ICPR), the Central Commission for Navigation on the Rhine (CCNR) and the International Commission for the Hydrology of the Rhine Basin (CHR). Water managers, research institutes and public authorities exchange data, carry out joint analyses and collaborate on strategies for drought, floods, water quality and climate adaptation.

Deltares is itself an official member of the CHR (and, together with Rijkswaterstaat, forms the Dutch delegation) and supports the ICPR and CCNR with expertise on water and the subsurface, as well as on water-related topics such as sediment transport, water quality and temperature, ecology, shipping movements, water use, etc. We take a holistic approach to this – integrating all facets – such as ecology, agriculture, industry, drinking water, socio-economic developments and climate trends – into a single coherent system to ensure sustainability and resilience

Collaboration in EU STARS4Water

The Rhine and Meuse river basins are not the only ones in which researchers, national governments, river commissions and other stakeholders are collaborating on water security and resilience, and on how to cope with all kinds of changes. Within STARS4Water too – where the Rhine is one of the focus areas – researchers, river commissions and other stakeholders from various countries are working closely together on new scenarios, data services and modelling tools to better understand and anticipate future water shortages.

On the Danube – which flows through 10 countries and therefore requires cooperation between even more countries – the wflow and Ribasim modelling software packages developed by Deltares are being used, similar to those in use in the Netherlands specifically for the Meuse and the Rhine.

Cooperation in this area is also taking place with the Messara (Greece) and the Drammen catchment area (Norway). The co-creation of these models contributes to the development of a shared database and fosters transparency and trust in the analyses that are intended to underpin cross-border political decision-making.

Collaboration in JCAR ATRACE

In the cross-border knowledge programme JCAR ATRACE, led by Deltares, we are working with renowned international research institutions to develop applied knowledge on how to better prepare our countries. This includes extreme drought and low water levels, as well as flooding in the shared catchment areas of smaller rivers such as the Overijsselse Vecht, Oude IJssel, Roer and the Aa or Weerijs.

Much less is known about these than about the major rivers. Through cross-border stress tests on drought and flooding, we are jointly gaining an understanding of how dependent we are on our neighbours and which joint measures (e.g. retention, management, protection or early warning) are effective.

Do upstream countries also retain water for their own use?

A frequently asked question during dry periods is whether upstream countries are withholding water, resulting in less water reaching the Netherlands.

In practice, the situation is more nuanced. Countries take measures to protect their own populations, economies and natural environments from drought. This can be achieved, for example, through reservoirs, water conservation or adjusted water distribution. These measures are not usually aimed at withholding water from downstream countries, but they can influence the amount of water that becomes available later on.

It is precisely for this reason that, within international partnerships, more and more research is being carried out into changes in the hydrological discharge regime – as the Rhine transitions from a glacial melt-fed river to a rain-fed river – as well as the effects of water use, reservoir management and water allocation across the entire catchment area. The recent CHR study shows that future water availability depends not only on climate change, but also, to an ever-greater extent, on the choices people make regarding water use and water distribution.

Can’t we make binding agreements on a minimum amount of water?

International rivers such as the Rhine are already managed under treaties and cooperation agreements. There are agreements, whether formal or informal, on water quality, information exchange, monitoring and joint preparedness for extreme situations.

Establishing a guaranteed minimum flow is complex. During prolonged droughts, there may simply be insufficient water available to meet fixed quantities everywhere. Furthermore, the interests of drinking water, nature, agriculture, industry and shipping vary from country to country and from region to region.

The CHR SES study highlights that water allocation and the prioritisation of water use are becoming increasingly important issues. The study concludes that this will require greater international consultation and joint agreements in the future.