“Thinking of Holland I see broad rivers slowly going through endless lowlands, rows of unimaginable slender poplars like tall plumes standing at the horizon.”
The opening lines of Marsman’s poem show that fresh water is inseparably connected to the Netherlands. About 18% of the Netherlands consists of water, and 14% of that is fresh water.
Fresh water is important because it enables life at the cellular level, supports oxygen production, food production, climate regulation, and biodiversity. It is this last aspect we want to focus on: the relationship between biodiversity and fresh water in the Netherlands, the threats to it, and the opportunities.
What does fresh water have to do with biodiversity? A lot. Less than 1% of all water on Earth is available as fresh water, yet about 10% of all known species live in it. The same applies to the Netherlands.
About 40% of freshwater biodiversity in the Netherlands consists of bacteria, microscopic algae, and plankton. These form the basis of all food chains. Roughly 20% consists of aquatic plants and macroalgae, 20% of small animals, 10% of fish, and finally 10% of larger animals such as the green frog, grey heron, and otter. The larger animals are at the top of the food chain and are often indicators of a healthy ecosystem.
What are the main threats to freshwater biodiversity? According to the IPBES drivers — the main causes of biodiversity loss and ecosystem change identified by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services — there are five direct drivers:
- Changes in land and sea use Examples include deforestation, urbanization, agricultural expansion, and soil excavation. Globally, this is often the biggest driver. In the Netherlands, it also includes canalization and dam construction, which lead to habitat loss.
- Direct exploitation of organisms and natural resources Overfishing, hunting, logging, and overharvesting of plants and animals. Excessive extraction of fresh water also falls under this category.
- Climate change Changes in temperature, precipitation, sea level, and extreme weather events that affect species and ecosystems.
- Pollution Nitrogen deposition, pesticides, plastics, chemicals, and nutrient
- Invasive alien species Species that enter an ecosystem from outside and displace native species, such as Japanese knotweed or the American
Driver 1 – Change in Land and Sea Use
Land use determines how water flows, how it is retained, and how clean it remains. When rainwater cannot infiltrate the soil properly due to urbanization or intensive agriculture, the risk of flooding increases and groundwater replenishment decreases. Flooding can be positive for biodiversity — think of floodplains — but extreme or unnatural flooding often is not.
Groundwater is essential for biodiversity; it acts as a hidden water reserve that sustains nature during dry periods, keeping plants and animals alive and feeding streams, rivers, and wetlands.
The Veluwe, for example, consists mainly of sandy soils and glacial ridges. Rainwater quickly seeps deep into the ground, forming a large groundwater buffer. Research shows that the historical conversion of heathland to pine forest caused a major decline in groundwater replenishment in the Veluwe. Land use changes have had a direct impact on groundwater and thus on biodiversity.
Land use determines how water flows, how it is retained, and how clean it remains. When rainwater cannot infiltrate the soil properly due to urbanization or intensive agriculture, the risk of flooding increases and groundwater replenishment decreases. Flooding can be positive for biodiversity — think of floodplains — but extreme or unnatural flooding often is not.
Groundwater is essential for biodiversity; it acts as a hidden water reserve that sustains nature during dry periods, keeping plants and animals alive and feeding streams, rivers, and wetlands.
The Veluwe, for example, consists mainly of sandy soils and glacial ridges. Rainwater quickly seeps deep into the ground, forming a large groundwater buffer. Research shows that the historical conversion of heathland to pine forest caused a major decline in groundwater replenishment in the Veluwe. Land use changes have had a direct impact on groundwater and thus on biodiversity.
Driver 2 – Direct Exploitation
The link with water is clear in the case of overfishing. The eel population is a striking example. Eels reproduce only once in their lifetime. When many adult eels are caught before they migrate to the sea to spawn, fewer young eels return. Eel reproduction as a migratory species also depends on water connections. Over time, many barriers have been built in the Netherlands — locks, pumping stations, weirs, and dams. Today, there are about 60,000 of these structures.
Since the 1960s, the eel population has declined by more than 90–95%. Land consolidation and efficient water management have increasingly closed off waterways for free fish migration.
Freshwater extraction in the Netherlands is another threat to monitor. The Rhine is a major source of fresh water. Although supply is not expected to decrease in the coming decades, it will become less stable throughout the year. Melting glaciers provide more water now but are natural storage buffers for warm, dry summers. Rainfall as a source of fresh water also becomes more volatile with rising temperatures.
Freshwater use in the Netherlands is roughly 50% for industry, 25% for households, 15% for agriculture, and 10% for purposes such as cooling power plants. Although the Netherlands has abundant fresh water, ecosystems can still come under pressure during dry summers.
Driver 3 – Climate Change
Climate change and water are inseparable. Global warming intensifies the water cycle. Higher temperatures cause more evaporation from rivers, soil, and plants, leading to drier ground.
Warmer air can hold more water vapor, resulting in longer dry periods but heavier rainfall when it does rain. Droughts and floods can both occur.
Melting ice and warming ocean water cause sea levels to rise. For the Netherlands, this has major consequences for coastal protection, groundwater salinization, dune ecosystems, and freshwater availability.
Warmer ocean water also causes species to migrate. In the North Sea, fish species are shifting further north. Moreover, warmer water holds less oxygen, stressing ecosystems — coral bleaching and death are examples. Warm surface water mixes less with cold deep water, reducing nutrient upwelling (nitrate and phosphate). Fewer nutrients mean fewer large plankton species and lower overall productivity.
In the Netherlands, warmer water and longer growing seasons increase the risk of blue-green algae blooms in inland waters, which harm biodiversity by causing oxygen depletion for fish and other aquatic animals.
Driver 4 – Pollution
Water often ends up being the final destination for pollution — chemicals, excessive nutrients like nitrogen and phosphate, plastics, pharmaceutical residues, and oil. In the 20th century, the Rhine was heavily polluted by industry, agriculture, and cities. Discharges of chemicals and wastewater caused massive fish deaths and the disappearance of sensitive species. Since the 1980s, international cooperation, stricter environmental regulations, improved water treatment, and ecological restoration have greatly improved water quality, allowing species like salmon to return.
Pollution not only causes direct mortality but also reduces reproduction, destabilizes ecosystems, increases disease, destroys habitats, and disrupts food chains — leading to long-term and sometimes irreversible biodiversity loss.
Driver 5 – Invasive Species
In water, invasive species can spread quickly and damage biodiversity. They disrupt ecosystems, displace native species, and introduce new diseases. A well-known example is the American crayfish, common in Dutch ponds and ditches, which spreads crayfish plague.
From Threats to Opportunities
What opportunities exist for companies to protect, restore, or improve freshwater biodiversity in the Netherlands through products and services?
Across sectors, several opportunities arise. To connect this to investment, each solution is linked to a publicly listed company active in Europe. In Amsterdam, companies such as DSM-Firmenich, AkzoNobel, Wavin, Boskalis, ING Group, and Ahold Delhaize are listed.
Wavin, for instance, develops systems for rainwater collection, storage, reuse, drainage, and filtration. It works with blue-green solutions that integrate water and nature. The TreeTank system is a smart urban solution combining trees, water management, and soil structure. Installed underground, it consists of crate-like structures around tree roots that collect rainwater from streets and roofs, slowly release it to the tree, protect roots, and provide space to grow. This way, rainwater is reused, and the lifespan of city trees is extended.
In private markets, regenerative agriculture is an attractive investment category. By using cover crops, the soil absorbs more rainwater and releases it slowly to plants and groundwater. This reduces drought stress, increases groundwater replenishment, and decreases peak runoff during rainfall.
Regenerative agriculture also improves water quality, as fewer pesticides and fertilizers enter the water compared to conventional farming. It benefits farmers and biodiversity, as well as drinking water companies through lower purification costs — and society as a whole.
Sustainable forestry offers similar benefits. The SLM Silva Europe Fund, for example, invests in land and rivers around water sources. Forests, like regenerative agriculture, improve soil infiltration and reduce water runoff. Better soil leads to higher and more stable yields over time, improved biodiversity, and greater climate resilience.
Finally, investments in water infrastructure — both traditional (such as water treatment and desalination plants) and nature-based (such as wetlands and floodplains) — are promising. These can also be combined: for instance, wetlands that filter wastewater after initial treatment in a plant. Or the French mineral water brand Vittel, which pays farmers to protect water quality in its catchment area.
“…and the sun is slowly smothered in grey, multicolored vapors, and in all regions the voice of the water that makes life possible is sought and heard.”
