The Una River

The Una River is recognised as an ecological gem within the "Blue Heart of Europe," best known for its unique cave-karst springs, travertine waterfalls, and healthy populations of the endangered Danube salmon (Hucho hucho). It springs from the Vrelo Une (the source of the Una) in Croatia, one of the world’s deepest springs, and flows 217 kilometres through Bosnia-Herzegovina and partly Croatia, before joining the Sava River. 

Together with its tributaries, including Krka, Unac, Klokot, Krušnica, Sana, and many others, it forms an interconnected karst river network without parallel in Europe. Around 650 kilometres of rivers and streams are distinguished by outstanding hydromorphological integrity, tufa cascades, waterfalls, and a rich diversity of aquatic habitats.

However, its current protection status is fragmented, leaving the vast majority of the Una and its tributaries vulnerable to contemporary development. While the sections of the Una and Unac rivers are already included in the existing Una National Park, the park’s strict protection zones mainly cover the surrounding forests rather than the rivers themselves, and the park’s management falls short of the IUCN’s international standards. Beyond the few remaining small hydropower projects, the greatest dangers come from unregulated construction along the banks and islands, water pollution, water abstraction, the impacts of growing mass tourism and, notably, a planned landfill for storing nuclear waste.

Una Science Week

Following seven days of intensive fieldwork, an international team of over 70 scientists and students has officially concluded Una Science Week. The mission of the week was, and is, to contribute to building a vision for protecting the Una River in its entirety, spanning 660 river kilometres. Assuming the Danube salmon, as the migrating flagship species, the aim is to show the importance of maintaining the health and connectivity of the Una’s diverse tributaries - from short but powerful karst streams like the Klokot and Krušnica, to meandering lowland rivers like the Japra, to the Ribnik-Sanica-Sana continuum that helps make the Una one of the region’s major rivers. 

The three core objectives are to: 

1. Demonstrate the resilience and conservation value of biodiversity contained in the portfolio of connected tributaries - from mosses to invertebrates, fish and humans.
2. Identify threats such as shoreline development and point-source pollution (fish farms, municipal sewage, a radioactive waste site).
3. Conceptualise a large-scale Una Wild River National Park grounded in a socio-ecological understanding of the river and designed to benefit both humans and nature.

What distinguishes Una Science Week from conventional scientific surveys is that its participating researchers do not merely collect and analyse data; they also act as independent advocates for the ecosystems they study, lending both scientific credibility and personal conviction to the case for protection.

Una Science Week: Scientists build the case for Europe’s next Wild River National Park