Free-flowing rivers across the Balkans, including Greece, are facing increasing pressure, according to a new 2025 regional scientific assessment.
The study links the trend to expanding infrastructure and hydropower development, which are fragmenting river corridors and reducing natural continuity. Greece still retains many relatively intact river systems compared with several neighboring countries, but researchers say the risk trajectory is now moving in the same direction.
The findings come from the Save the Blue Heart of Europe research campaign, which monitors river modification patterns and ecosystem connectivity across the region.
Regional loss of natural river corridors affects Greece’s rivers
Across the Balkans, researchers recorded a clear negative trend over the past 13 years. Since 2012, about 2,450 kilometers (1522,35 miles) of free-flowing river corridors have been lost, representing a 7 percent decline in natural river conditions.
The study reviewed 83,824 kilometers (52,0858 miles) of waterways across 11 countries, including Greece, and evaluated both water quality and ecological connectivity.
Scientists stress that connectivity, the ability of a river system to function without artificial barriers, is a core measure of ecosystem health alongside chemical status.
Why connectivity is critical for river systems
Experts note that clean water alone does not guarantee a healthy river. Physical continuity allows fish migration, sediment transport, and natural floodplain exchange. Dams, diversions, and channel barriers interrupt these processes and divide rivers into isolated segments.
While many European river systems are already heavily fragmented, the Balkans had long remained comparatively intact. The latest data shows that this advantage is narrowing. Between 2012 and 2025, river sections converted into artificial reservoirs increased by 18 percent, signaling intensifying development pressure.
Greece’s rivers condition in detail
According to the study’s classification, 35 percent of rivers in Greece still retain natural status. Another 33 percent show slight modification from mild human intervention. About 22 to 23 percent fall into extensively or significantly modified categories.
More than 3,500 kilometers (2,174 miles) of Greek river networks have undergone substantial alteration. The most heavily transformed stretches, about 4 percent, appear mainly along major river systems such as the Haliacmon and the Achelous.
Within the Balkan comparison, Montenegro ranks highest in ecological connectivity, while Greece groups near the regional midpoint alongside Croatia, Bosnia and Herzegovina, and Serbia. Albania shows one of the sharpest declines since 2012.
Hydropower expansion drives new fragmentation
The study identifies small hydropower projects as the main source of new river disruption across the Balkans. More than 1,800 hydropower plants currently operate in the region, with over 3,000 additional projects in licensing or planning stages.
In Greece, around 120 small hydropower facilities are already in operation, many concentrated in environmentally sensitive areas such as the Pindus mountain range. More than 500 further projects are under review. Despite their geographic spread, these plants produce only about 1.6 percent of the country’s electricity output.
Researchers support renewable energy development but argue that project siting rules need revision. Greece’s spatial planning framework for renewables dates to 2008, and specialists call for updated zoning that excludes high-value river ecosystems.
Climate pressure and policy response
Climate change adds further stress through a dual pattern of lower baseline river flows and more frequent extreme flood events. Many flood-control approaches still rely primarily on hard infrastructure, although experts point out that connected rivers and protected floodplains often provide more resilient long-term protection.
Policy attention is now shifting toward river restoration. An EU regulation adopted in August 2024 requires member states to restore 25,000 kilometers (15534 miles) of rivers by 2030. Greece is preparing its national restoration plan for submission to the European Commission this September, working with research organizations to identify priority reconnection areas while safeguarding rivers that still maintain strong ecological integrity.