Environmental Impact of Dam Removal within the Danube Biosphere Reserve

ANALYTICAL REPORT
Institute of Danube Research
Date: October 2025

1. Introduction

The anthropogenic transformation of river systems remains one of the most pressing environmental challenges in modern Ukraine. A particularly significant case is the removal of obsolete hydraulic structures within the Danube Biosphere Reserve, implemented in 2019 under the initiative of WWF-Ukraine, in partnership with the international Open Rivers Programme. This project forms part of the broader European initiative Dam Removal Europe, aimed at restoring the natural hydrodynamics of rivers and mitigating the ecological risks caused by fragmentation of aquatic ecosystems.

The purpose of this analytical report is to provide a systematic assessment of the ecological, hydrological, and socio-economic outcomes of dam removal in the Ukrainian Danube delta and to define its contribution to sustainable regional development.

2. Historical and Functional Background

During the second half of the twentieth century, several small dams and weirs were constructed on the Kogylnyk, Sarata, and Kagach rivers, which flow through the present-day Danube Biosphere Reserve. Their primary functions included:

• irrigation of agricultural lands;

• maintaining water levels for local water supply systems;

• regulating the flow within reclamation canal networks.

Over time, these hydraulic structures lost their functional significance and maintenance ceased. Consequently, they became drivers of ecological fragmentation, disrupting natural water circulation, impeding fish migration, and accelerating soil salinization. This led to the degradation of floodplain meadows, spawning areas, and wetland ecosystems.

3. Project Implementation

In 2019, ten obsolete dams and barriers were dismantled under the joint coordination of WWF-Ukraine and WWF Netherlands within the framework of the Dam Removal Europe initiative. The technical works were conducted under environmental supervision, adhering to the protection regime of the Danube Biosphere Reserve, which holds UNESCO international status.

The project became a pioneering example of river restoration in Eastern Europe, integrating scientific, engineering, and community-based approaches.

4. Ecological and Hydrological Outcomes

The removal of hydraulic structures triggered significant positive ecological transformations in the natural systems of the Danube delta. The main outcomes include:

1. Restoration of Hydrological Continuity.
   Continuous water flow was re-established along approximately 20 km of river channels, enhancing natural circulation, oxygenation, and sediment transport. This restoration reactivated the rivers’ self-cleaning capacity and reduced stagnation zones.

2. Improved Water Quality.
   Natural flow dynamics facilitated aeration and filtration, lowering the concentrations of suspended solids and organic matter. Monitoring confirmed improvements in water transparency, dissolved oxygen levels, and reductions in nutrient accumulation.

3. Recovery of Biodiversity.
   The removal of migration barriers allowed native and migratory fish species, including sturgeons, to return to traditional spawning routes. The overall diversity of fish, amphibians, and waterfowl increased, while new natural habitats were formed along riverbanks and floodplains.

4. Re-ecologization of Floodplain Landscapes.
   The reactivation of hydrological cycles led to the natural regeneration of meadows and wetlands, restoration of soil moisture levels, and reduction of salinization processes. These changes strengthened the ecological resilience of the biosphere reserve.

5. Socio-Economic Dimensions

Beyond ecological gains, the project produced tangible social and economic benefits:

• Mitigation of flood and dam failure risks, enhancing public safety;

• Expansion of opportunities for eco-tourism, sustainable fishing, and environmental education;

• Strengthening the ecological image of the region, improving conditions for international cooperation and funding.

The restoration of free-flowing rivers aligns with the objectives of the UN Sustainable Development Goals (SDGs 6, 13, 15) and the EU Strategy for the Danube Region (EUSDR), particularly Priority Areas PA4 (Water Quality) and PA6 (Biodiversity and Landscapes).

6. Scientific and Methodological Aspects

Monitoring conducted by the IDS demonstrates that the dam removal has reactivated key hydromorphological processes:

• seasonal variability of water flow has increased;

• sedimentation and nutrient exchange processes have been restored;

• local water balance has stabilized.

These findings confirm the long-term ecological efficiency of dam removal as a nature-based solution for the management of aquatic ecosystems. The project illustrates the value of integrating hydromorphological monitoring into environmental governance frameworks for biosphere reserves.

7. Conclusions

1. The removal of dams within the Danube Biosphere Reserve represents a successful case of ecological restoration in Ukraine.

2. The initiative significantly improved water quality, biodiversity, and ecosystem resilience across the region.

3. The outcomes support the integration of eco-oriented approaches into national and regional water resource management policies.

4. The experience has strong replicability potential for other river basins in Ukraine, including the Dniester, Southern Bug, and Siverskyi Donets.

5. Further research by the IDS should focus on quantifying ecosystem services recovered as a result of dam removal and conducting long-term monitoring of hydrological and biological indicators.

8. Recommendations

• Integrate the issue of obsolete dam removal into the National Water Resource Management Strategy of Ukraine 2030.

• Develop a regional program titled “Free Rivers of the Danube Lowlands”, focused on step-by-step restoration of river continuity.

• Enhance cooperation among IDS, WWF-Ukraine, the ICPDR, and the Ministry of Environmental Protection of Ukraine for unified post-removal monitoring.

• Support public awareness campaigns among local communities to promote understanding of the ecological and social benefits of river restoration.