A fragile Baltic watercourse faces mounting pressure as nuclear operations, military mobility projects, and ecosystem obligations collide.

The Viliya–Neris basin now holds overlapping nuclear, environmental, and strategic functions. Its role as a protected Natura 2000 corridor contrasts sharply with its use as the primary cooling source for the Belarusian NPP and with expanding Lithuanian military mobility infrastructure. These parallel trajectories introduce simultaneous ecological and geopolitical tensions.

Radiation risks from NPP incidents and the planned RWDF intersect with dredging plans, bridge upgrades, and navigation proposals that would alter the river’s morphology. The result is a concentrated transboundary pressure zone whose effects extend from Belarus and Lithuania through the Nemunas and into the already strained Baltic Sea system.

Chronology and Facts: Viliya/Neris – Risks of Militarization and Radiation Threat from Belarus and Lithuania

1. Introduction: The Viliya–Neris River – a unique, unified transboundary ecosystem of Belarus and Lithuania belonging to the Baltic Sea basin

The Viliya River, known in Lithuania as the Neris, forms a unified transboundary ecosystem of Belarus and Lithuania and belongs to the Baltic Sea basin. It is one of the largest surface water arteries in the region: its total length is about 510 km, and the basin area is approximately 25,000–25,100 km², roughly half of which lies in Belarus and half in Lithuania¹. Viliya/Neris originates on the Minsk Upland in the northern part of Belarus, flows through the Vileyka Reservoir, then passes through Vilnius, and empties into the Nemunas near Kaunas, after which, through the Nemunas, it is connected to the Baltic Sea. Thus, the same river system physically links Belarus, Lithuania, and further the Baltic basin.

From a political standpoint, Viliya/Neris is a unique water corridor connecting countries currently in a state of acute political and military confrontation: Belarus, Lithuania, and, through the Nemunas and the Baltic Sea, Russia, Poland, and other coastal states. A map of the Baltic region clearly shows that the river basin lies at the very center of the “contact zone” between NATO and the Union State of Russia and Belarus². Unlike many other transboundary rivers, Viliya/Neris remains relatively unmodified along its course (especially upstream of Vilnius), preserving natural meanders, floodplain meadows, and forests – a fact highlighted in Lithuanian environmental impact assessment (EIA) documents³ and protected-area reports.

From an ecological standpoint, the Neris valley in Lithuania is included in the European Natura 2000 network as a site of pan-European importance: it protects a complex of riparian and floodplain habitats, including floodplain meadows, alluvial forests, and riparian spruce and deciduous forests, as well as species listed in the EU Habitats Directive and Birds Directive⁴. According to Lithuanian researchers, as cited in environmental assessments of the Neris near Vilnius⁵, more than 30 key species of animals and plants have been recorded in the river ecosystem and adjacent territories, including rare species of fish, birds, and mammals. Among the protected species for which the Viliya–Neris valley serves as an important habitat or migration corridor are, for example, the otter (Lutra lutra), the beaver, several species of birds of prey (such as the European honey buzzard Pernis apivorus and the lesser spotted eagle Clanga pomarina), as well as the European mink and several species of bats.

The ichthyofauna of Viliya/Neris is characterized by high species richness: according to studies from the late 1990s⁶ and later assessments, several dozen species of fish inhabit the river – ranging from typical cold-water river species (grayling, chub, roach, ide) to representatives of salmonids and whitefish. In Belarus it is the most fish-rich river, with around 60 fish species recorded. Key spawning grounds are located in the Viliya and its connected water bodies. An IAEA report on the Belarusian NPP⁷ explicitly notes that “the ichthyofauna of the Viliya River is no poorer than that of the Nemunas basin as a whole,” and that the specific total fish biomass is about 130–140 kg/ha. This is also confirmed by Belarus’s National Biodiversity Strategy⁸, which states that river ecosystems of the Nemunas basin, including the Viliya, support dozens of fish species and essential spawning sites.

Of particular importance is the fact that the Nemunas–Viliya system remains one of the last fully functioning migration corridors for wild Baltic salmon and sea trout, allowing them to spawn in the upper reaches, including areas adjacent to Belarus. A 2021 report by the Coalition Clean Baltic (CCB) and partners on dam removal in the Baltic Sea region⁹ directly states that “sea trout and salmon migrate from the Baltic Sea and return to Belarus via the Nemunas and the Viliya; natural salmonid spawning grounds in Belarus are linked specifically to this river system.” At the same time, the same report and Lithuanian analyses emphasize that many other historical salmon migration routes in the Nemunas basin have been blocked by hydropower dams, making the preservation of free-flowing segments of Viliya/Neris critically important for the entire Baltic salmon population.

Viliya/Neris is also important as a “last-chance ecological corridor” not only for fish but for entire complexes of floodplain ecosystems: along the river lie migration routes and stopover sites for numerous species of waterfowl and semi-aquatic birds, including geese, ducks, waders, and herons, as well as nesting sites of rare species listed in the Red Data Books of Lithuania and Belarus¹⁰. Riverbanks preserve sections of floodplain forests and meadow-pasture complexes, which EU habitat documents classify as priority habitats because they simultaneously store carbon, regulate the local climate, and serve as buffers against flooding.

The Baltic Sea, to whose basin Viliya/Neris belongs, is itself an extremely vulnerable and heavily burdened ecosystem – overloaded by militarization and past wars. It is the world’s largest almost-enclosed brackish sea, covering about 377,000–432,000 km² and connected to the North Sea only by the narrow Danish straits. More than 250 rivers, including the Nemunas, flow into it. As shown in the latest comprehensive review, State of the Baltic Sea 2023 by the HELCOM¹¹ Baltic Marine Environment Protection Commission, the Baltic Sea faces simultaneous pressures from eutrophication (excessive nitrogen and phosphorus), hazardous substances, overfishing, underwater noise, and climate change; according to NIB¹², most of the Baltic Sea surface is affected by eutrophication, making it one of the most polluted seas on the planet.

To this is added the military legacy of the 20th century: according to HELCOM MUNI, after World War II, around 40,000 tons of chemical munitions containing about 13–15 thousand tons of toxic agents were dumped into the Baltic Sea¹³. Additional assessments of “hazardous submerged objects” and potentially polluting shipwrecks¹⁴ show that the seabed of the Baltic remains a source of persistent pollutants, including heavy metals and organic toxins. The combined impact of eutrophication, hazardous substances, and dumped munitions has led to the Baltic Sea¹⁵ being recognized as one of the most polluted seas in the world.

In this context, Viliya/Neris is not “just another river,” but a critically important link in the region’s entire water system. Any deterioration of its condition (through militarization of the riverbed, dredging operations, radiation load from the Belarusian NPP, or the future radioactive waste repository) automatically affects the state of the Baltic Sea. Conversely, preserving the natural integrity of Viliya/Neris is one of the few available tools for strengthening the resilience of the Baltic ecosystem, supporting salmon migration routes and other species, and demonstrating in practice that even under geopolitical confrontation a transboundary river can be a priority zone for cooperation rather than military use.

Viliya/Neris as a Node of Three Functions and Three Threats

Today, the Viliya/Neris River simultaneously performs three fundamentally different functions, each of which is established in official documents of Belarus, Lithuania, and the EU:

• a key element of the pan-European network of protected areas,

• the main source of technical water for the Belarusian Nuclear Power Plant,

• part of the “military mobility” infrastructure and a potential evacuation corridor within national and European defense plans.

It is precisely the combination of these three roles within a single transboundary river system that forms a uniquely large and complex configuration of risks for the river ecosystem, public health, and regional security architecture.

i. Protected natural area of European importance (Natura 2000)

In Lithuania, the Neris valley is officially included in the Natura 2000 network as a site of European importance. This is recorded in the standard Natura 2000 data form for the relevant areas (including Neries regioninis parkas and associated “Neris valley” segments), approved by the Lithuanian State Service for Protected Areas and coordinated with the European Commission as part of the implementation of the Habitats Directive and Birds Directive.

Natura 2000 status means that:

• specific types of natural habitats listed in the annexes to the Habitats Directive are protected (e.g., floodplain meadows, alluvial forests, riparian spruce and deciduous forests, and natural segments of the river channel with characteristic riffles and rapids);

• species listed in EU directives are protected, including the otter (Lutra lutra), several species of bats, rare birds of prey (the European honey buzzard Pernis apivorus, the lesser spotted eagle Clanga pomarina, and others), as well as key ichthyofauna species;

• any projects (construction, dredging, channel modification, hydraulic structures) that could significantly affect the integrity of the area are subject to strict environmental impact assessment, and may be approved only under exceptional circumstances and with compensatory measures at the EU level.

Thus, within the EU legal framework, the Neris is regarded as a “priority zone for biodiversity conservation,” not as an object for infrastructure or military use. Attempts to redefine its functions without considering Natura 2000 status directly call into question Lithuania’s fulfillment of obligations under EU law.

ii. The main source of technical water for the Belarusian NPP and the future RWDF

Official environmental impact assessment (EIA) materials for the Belarusian NPP, submitted by Belarus¹⁶ under international procedures (including the Espoo Convention), explicitly designate the Viliya as the main and essentially the only large source of technical water for the reactor cooling system. Water intake and discharge occur through hydraulic structures connecting the NPP with the river channel.

Project documents and subsequent reviews emphasize that:

• Viliya water is used to supply circulation and make-up systems, as well as for other technical needs of the plant;

• the return flow (even under normal operation) alters the thermal and chemical regime of the river downstream of the water intake;

• in emergency situations (leaks, system breaches, discharge of accident-contaminated water), the Viliya becomes the primary recipient of potential radioactive contamination, which would subsequently be transported into Lithuania and further through the Nemunas–Baltic system.

Additionally, Belarus is moving forward with the creation of a radioactive waste disposal facility (RWDF) in the Astravyets district – within the Viliya basin. Official decisions on the designated state contractor, design development, and site preparation have been formalized in regulatory acts (including a presidential decree appointing responsible entities). An RWDF located in a hydrogeologically connected zone will remain a long-term potential source of radioactive contamination of groundwater and, through them, the Viliya channel, for decades and centuries.

Thus, the same river system simultaneously supports an operational nuclear installation and a planned radioactive waste repository – structurally increasing both current and cumulative radiation risk.

iii. An element of the “military mobility” and evacuation infrastructure

In Lithuania, the Neris is increasingly viewed as a component of defense and civil-protection infrastructure. This is reflected in both national documents and projects potentially funded by EU mechanisms.

On one hand, bridges over the Neris and adjacent road sections are included in the list of dual-use infrastructure being modernized through EU “military mobility” initiatives and national budget allocations. Government resolutions (including funding for reconstruction of bridges and road segments along the A1 motorway) directly link these projects to enabling military transit and rapid deployment of NATO allied forces¹⁷.

On the other hand, in public statements by the Mayor of Vilnius and municipal officials, the Neris is described as a potential evacuation route for the population in the event of military or nuclear threat. Measures under consideration include:

• removal of natural rapids and stone riffles (initially estimated at six) to ensure navigability;

• dredging and channel straightening operations that could transform the river’s natural morphology;

• integration of the river into a system of more than 150 evacuation routes linking Vilnius with other regions of Lithuania.

As a result, Viliya/Neris is being effectively shifted into the category of a strategic “military mobility” and civil-defense object. This means that the river is increasingly viewed through a militarization lens – logistics and evacuation – rather than ecological value and international conservation obligations.

Configuration of the “three threats”

At the intersection of these three functions – protected area, nuclear infrastructure, and military mobility – emerges a systemic configuration of “three threats,” which distinguishes Viliya/Neris from most other transboundary rivers in the region:

Operational radiation threat from the Belarusian NPP.

The continuous operation of a nuclear facility with a history of incidents – and which uses the Viliya as its primary source and potential recipient of water – creates the risk of sudden, acute contamination scenarios (accidents, leaks, emergency discharges), as well as chronic thermal and chemical stress on the river ecosystem.

Long-term threat from the planned RWDF.

A radioactive waste repository in the Astravyets district, hydrogeologically connected to the Viliya basin, poses a long-term risk: radioactive elements could enter groundwater and the river years or decades later, even after NPP operations cease, affecting the entire Viliya/Neris flow down to the Nemunas and the Baltic.

Geopolitical threat from militarization of river infrastructure and military-mobility projects.

The reorientation of Viliya/Neris and its infrastructure (bridges, roads, and potentially the riverbed) for military mobility and evacuation turns the river into a strategic object and potential target during conflict, encourages engineering interventions incompatible with Natura 2000 conservation goals, and increases overall militarization pressure in the region.

Taken together, these three vectors – operational and long-term radiation risks, and geopolitical-military risks – create a unified zone of heightened transboundary danger. Viliya/Neris ceases to be “just a river” in national terms and becomes a critical fault line between ecological obligations, nuclear energy, and military logistics at the heart of the Baltic region.

2. Belarus: Belarusian NPP and the Radioactive Waste Repository in the Viliya/Neris Basin

2.1. Chronic Operational Threat from the Belarusian NPP (Astravyets)

The Belarusian Nuclear Power Plant (BelNPP) is located less than 50 km from Vilnius and uses the waters of the Viliya River as its main – and virtually only – large source for its cooling system, as confirmed by EIA documents and relevant European reviews¹⁸. This creates a direct route for radioactive substances to enter the river system in the event of an emergency leak or non-routine discharge.

Since 2016, a series of incidents has been recorded, reflected in official statements by Lithuania’s Ministry of Foreign Affairs, European institutions, specialized reports, and media sources:

• 08 April 2016 – damage to load-bearing structures during the installation of a span between the reactor buildings¹⁹.

• 10 July 2016 – the reactor vessel of Unit 1 was dropped from a height of about 4.5 meters during movement²⁰.

• 26 December 2016 – collision of the reactor vessel of Unit 2 with a railway catenary support during transportation²¹.

• 08–10 November 2020 – emergency shutdown of electricity production shortly after launch due to explosions of several voltage transformers²² (according to media reports).

• 16 January 2021 – Unit 1 disconnected from the grid due to activation of the generator protection system²³ (according to media reports).

The European Parliament, in its 11 February 2021 resolution, expressed concern over the frequency of incidents at the Belarusian NPP (noting at least eight incidents during construction and commissioning), stated that this indicates “quality issues,” and underlined the need for an early-warning system for Lithuania regarding radiation threats (EUR-Lex 52021IP0052)²⁴.

The European Nuclear Safety Regulators Group (ENSREG) published peer-review reports in 2021 containing a list of recommendations, many of which remain under monitoring²⁵.

In 2023–2025, new shutdowns and failures were recorded, including:

• 23 January 2025 – statement by Lithuania’s regulator VATESI (State Nuclear Power Safety Inspectorate) that the Belarusian NPP continues to operate with disruptions and with “unresolved safety problems”; at the time of the statement, both units were offline²⁶.

• 17 July 2025 – Unit 2 disconnected from the grid following a signal indicating an “anomaly in the non-nuclear part of the cooling system” (cited by Reuters²⁷).

• 23 July 2025 – repeated disconnection of Unit 2 due to a malfunction in the generator cooling system²⁸ (charter97.org; official communications stressed that radiation levels were normal).

Thus, the operational history of the Belarusian NPP is characterized by recurring incidents, insufficient transparency, and persistent regulatory concerns – creating a background of chronic radiation risk for the Viliya/Neris basin.

2.2. Plans for a Radioactive Waste Disposal Facility (RWDF) in the Astravyets District

Belarusian authorities have officially declared their intention to build a radioactive waste disposal facility (RWDF) near the Belarusian NPP:

• October 2022 – public discussion of the “Radioactive Waste Management Strategy,” acknowledging the need to build an RWDF²⁹.

• 2024–2025 – representatives of Gosatomnadzor and the Ministry of Emergency Situations (MES) stated that a site for the RWDF would be selected during 2025³⁰.

• June–August 2025 – the Ministry of Energy announced that three areas were under consideration for the facility, with priority given to the Grodno region (Astravyets district)³¹.

• October 2025 – Presidential Decree No. 349 appointed the project’s customer (the Republican Unitary Enterprise “Belarusian Radioactive Waste Management Organization”) and the general contractor (JSC “Belenergostroy”), marking the transition to the stage of practical implementation³².

According to Belarusian sources and independent investigations (including the BELPOL initiative), the most likely RWDF location is planned in the Astravyets district, approximately 22 km from the Lithuanian border, within the Viliya basin. In the event of leaks (due to container degradation, geological factors, or external impacts), radionuclides may enter groundwater hydrogeologically connected with the Viliya River, resulting in the transport of contamination into Lithuania and the Baltic Sea.

3. Lithuania: Military Mobility Projects and the Concept of the Neris as an Evacuation and Military Corridor

3.1. National and European Military Mobility Projects

In 2024–2025, Lithuania has been consistently expanding its military mobility infrastructure, including facilities directly connected to the Neris River:

• 11 September 2024 – the Government of Lithuania allocated an additional EUR 42.3 million for military mobility (dual-use) projects, including EUR 15.3 million for the reconstruction of the middle bridge over the Neris on the A1 motorway section (99.03–100.47 km). The official goal is the adaptation of transport infrastructure for military needs³³.

• 03 July 2025 – within the Rail Baltica project, the EU’s Connecting Europe Facility (CEF) provided EUR 295.5 million in funding, including construction of a new bridge over the Neris as part of strategic military infrastructure³⁴.

These documents confirm the reclassification of a portion of Neris-related infrastructure from purely civilian to strategic military mobility assets.

3.2. Neris as a Potential Evacuation Channel

In 2024–2025, the city of Vilnius has been developing population evacuation plans for scenarios of military or nuclear threat:

• 19 January 2025 – in an interview with LRT, Mayor of Vilnius Valdas Benkunskas stated that “one of the evacuation routes from the capital could be via the Neris River”; consultations with the army were mentioned, as well as an estimated cost of around EUR 10 million for removing six rapids to ensure navigability³⁵.

• 23 April 2025 – BBC News published material on Vilnius’s evacuation plan, noting 150 routes, including possible use of the Neris as a corridor leading westward to Klaipėda and Kaunas³⁶.

At the same time, researchers from Vilnius University and environmental NGOs warn that any large-scale dredging, straightening of the river channel, or removal of stone rapids would disrupt natural river dynamics and contradict Lithuania’s and the EU’s obligations to protect the Neris valley as a Natura 2000 site.

Separately, concerns have been raised regarding the risk that funds intended for environmental protection (such as programs associated with Natura 2000) could be used to finance activities that effectively contribute to the militarization of the river, contradicting the objectives of these instruments.

4. Combined Transboundary Risk for the Viliya/Neris Basin and the Baltic Sea

Radiation vulnerability:

The Belarusian NPP, which uses the Viliya for cooling, already has a history of numerous incidents and incomplete implementation of ENSREG and EU recommendations. The planned RWDF in the Astravyets district creates a long-term risk of radionuclide migration into groundwater within the Viliya basin.

Militarization of the Neris riverbed:

Military mobility projects, bridge reconstruction, and discussions about transforming the Neris into a navigable evacuation channel shift the river into the category of a strategic object and potential target. This increases the risk of damage in the event of conflict and intensifies ecological stress due to dredging and engineering interventions.

Baltic Sea context:

Viliya/Neris flows into the Nemunas and thereafter into the Baltic Sea – already the most polluted sea in Europe, burdened by submerged military remnants, industrial discharges, and climate stressors. Any major contamination in the Viliya/Neris basin (whether radioactive, chemical, or otherwise) further strains the closed Baltic ecosystem.

Taken together, this creates a systemic transboundary risk in which actions by Belarus and Lithuania regarding the same river – operation of the Belarusian NPP and RWDF on one side, and militarization of the riverbed on the other – reinforce each other and require a comprehensive international response.

5. Preliminary Conclusions and Recommendations for International Bodies

For the Parties to the Espoo Convention and the UNECE Water Convention

• Initiate an updated joint assessment of the transboundary impact of the operation of the Belarusian NPP and the planned RWDF on the Viliya/Neris basin, with an emphasis on hydrological pathways of possible contamination spread.

• Consider the need for an additional consultation procedure regarding the RWDF plans in the Astravyets district and the projects related to dredging of the Neris in Lithuania, treating them as unified transboundary objects.

For EU institutions (European Commission, European Parliament, ENSREG)

• Continue monitoring the implementation of ENSREG recommendations and the 2021 European Parliament resolution on the Belarusian NPP, paying particular attention to water use and radioactive waste management plans.

• Verify the compliance of EU funding (including Natura 2000 programs and military mobility funds) with obligations to preserve the Viliya/Neris valley as a Natura 2000 site and with EU environmental law requirements.

For regional marine mechanisms (HELCOM and others)

• Include on the agenda the issue of the impact of radiation-related and militarization-related projects in the Viliya/Neris basin on the ecological state of the Baltic Sea.

• Consider developing a special subregional plan for managing risks related to transboundary rivers with potential for radioactive contamination.

For the authorities of Lithuania and Belarus

Lithuania:

Exclude dredging and channel-straightening works on the Neris within military mobility and evacuation projects, ensuring the priority of the Neris valley’s protected status and compliance with Natura 2000 obligations.

Belarus:

Reconsider the location and parameters of the RWDF, taking into account the hydrological connection to the Viliya, and ensure full implementation of international recommendations on the safety of the Belarusian NPP, including continuous access for independent experts for monitoring and expert assessment.