Significant Improvement in the Microbiological Quality of the Danube — First Results of the Largest Danube Survey

Vienna (OTS) — The sampling campaign launched in July within the framework of the Joint Danube Survey 5 (JDS 5) — the world’s largest research programme dedicated to a major river — has been successfully completed. Samples were collected as planned at 108 monitoring stations across the Danube Basin, and laboratory analyses are currently underway. The first results of microbiological monitoring are now available and indicate an overall positive trend.

Austria’s Minister for Water Resources, Norbert Totschnig, emphasized that initial assessments confirm the Danube is in a significantly better condition than several years ago. According to him, microbiological pollution of the Danube has decreased by 86% over the past 25 years, reflecting the success of targeted international cooperation and sustained investments in wastewater infrastructure. Austria is financing approximately 50% of the total survey budget of EUR 600,000.

JDS 5 is coordinated by the International Commission for the Protection of the Danube River (ICPDR) and implemented jointly by 14 Danube Basin countries, involving more than 1,000 experts from over 100 institutions. The survey covers the Danube main channel, major tributaries, groundwater bodies, riparian and floodplain areas, as well as selected wastewater treatment plants.

The programme includes comprehensive analyses of:

-       chemical water parameters (nutrients, pollutants, heavy metals);

-       large-scale screening for thousands of substances, including “emerging pollutants”;

-       biological quality elements (fish, invertebrates, algae, aquatic plants, plankton);

-       microbiological indicators (faecal pollution, pathogens);

-       advanced parameters such as environmental DNA (eDNA), microplastics, radioactivity and rare earth elements;

-       hydromorphological conditions and groundwater monitoring.

Initial results show that Austria maintains a high water quality level, with low to moderate pollution, although localised peaks were detected near wastewater treatment plants and marinas. At the same time, Eastern EU Danube countries demonstrate substantial improvements, with many river sections previously classified as heavily polluted now falling within the “green” quality range.

The microbiological component is conducted under Austrian scientific leadership by the ICC Water & Health consortium (Medical University of Vienna, TU Wien and Krems), in cooperation with partner institutions from across the Danube region. Continuity of research since JDS 2 (2007) enables unique long-term comparisons.

The collected data will form the scientific basis for the Danube River Basin Management Plan 2027. Further results — including chemical pollution, hydromorphology, microplastics, eDNA and groundwater quality — are expected in 2026, with the final technical report of JDS 5 scheduled for publication in early 2027.

Commentary by the Institute of Danube Research

The interim results of JDS 5 clearly demonstrate the effectiveness of long-term, science-based water governance in the Danube Basin. An 86% reduction in microbiological pollution confirms that sustained investments in wastewater treatment and harmonised EU environmental standards deliver measurable results.

For Ukraine and the Lower Danube region, these findings are particularly important in the context of post-war recovery, climate adaptation and integration into European water policy. The incorporation of JDS 5 results into the Danube River Basin Management Plan 2027 creates new opportunities for targeted environmental protection, safeguarding delta ecosystems and ensuring the sustainable development of the Danube region.