New analysis warns: Vorarlberg's rivers are losing water dramatically
A recent analysis by Greenpeace shows that significantly less water flows in most Austrian rivers in summer than 20 years ago.
Vorarlberg's rivers Lech, Rhine, and Ill are particularly affected by this development, with water levels declining between 10 and 16 percent. The analysis of over 78,000 measured values from 18 rivers reveals a worrying trend that could have far-reaching consequences for ecosystems and water supplies.
The study compares the summer months of two periods: 1977 to 1999 and 2000 to 2022. The result is clear – the water volume has decreased in 15 of the 18 rivers examined. The situation is particularly dramatic at the lowest water levels: In the Ill, the summer minimum values have fallen by about a quarter, in the Rhine by a fifth, and in the Lech by around 17 percent.
The Rhine, which forms the border between Vorarlberg and Switzerland, is of central importance to the province. Almost 90 percent of the state's area lies within its catchment area, meaning that most of Vorarlberg's rainwater and meltwater flows into it.
The decline is particularly evident at the "Lustenau" measuring station: In the summers between 1977 and 1999, an average of about 311 cubic meters of water flowed per second. In the comparable period from 2000 to 2022, the figure was only around 273 cubic meters per second—a decrease of about twelve percent.
Even more alarming are the monthly lows, which have declined by around 21 percent. This represents the fourth-largest decline in monthly minimums of all rivers studied.
The Ill, the longest river in Vorarlberg, originates in the Silvretta group and flows into the Rhine below Feldkirch.
A similarly worrying trend is evident at the "Gisingen" measuring station: In the summers from 1977 to 1999, an average of about 89 cubic meters of water flowed per second. In the summers between 2000 and 2022, this value fell to around 79.5 cubic meters per second—a decrease of about ten percent.
The monthly lows appear particularly dramatic, having declined by around 25 percent. This means that on its lowest-flow days since 2000, the Ill River carries only three-quarters of the volume of water it had on comparable days in previous decades. This is the third-largest decline among all rivers studied.
The Lech River, which originates in Vorarlberg and flows through Tyrol into Germany, is also experiencing a significant decline in water flow. At the "Steeg" measuring point, an average of 18.35 cubic meters of water per second flowed in the summers between 1977 and 1999.
Between 2000 and 2022, this value fell to 15.41 cubic meters per second—a decrease of approximately 16 percent. This represents the third-largest decline in daily mean values of all rivers examined. The monthly minimum values also show a similar decline of approximately 16 percent.
In contrast to the other rivers, the Bregenzerach is showing a positive development. As the second longest river in Vorarlberg, it originates in the Lechquellen Mountains and flows into Lake Constance between Bregenz and Hard.
At the "Kennelbach" measuring station, an average of about 46 cubic meters of water per second flowed in the summers between 1977 and 1999. In the comparable period from 2000 to 2022, the flow was even slightly higher – around 46.5 cubic meters per second, an increase of 1.4 percent. The monthly lows show an even more significant increase of about 19 percent.
Thomas Hein of BOKU warns of the negative impacts on the life in flowing waters. Rising water temperatures combined with decreasing flow rates in the summer months pose a serious threat to aquatic ecosystems.
"These changes affect Austria's regions differently, and the trend will continue in the coming decades. Therefore, we as a society must act decisively now," Hein emphasizes.
Greenpeace is calling on Agriculture Minister Norbert Totschnig (ÖVP) to rapidly implement a package of measures. This includes a transparency register for water withdrawals, an ambitious water strategy, and accelerated renaturation projects.
The goal is clear: rivers should be able to hold more water in the region even in dry periods in order to minimize ecological damage and secure the water supply in the long term.
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