Reduction in residual water volumes did not have the desired effect
Published: Thursday, Nov 30th 2023, 12:20
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The relaxed flow regime for hydropower plant operators last winter had less of an impact than hoped for. Electricity production only increased by 26 gigawatt hours instead of the estimated 150 gigawatt hours. At the same time, endangered fish species were less able to reproduce.
These are the main findings of a study conducted by the Federal Office for the Environment (FOEN), which was published on Thursday. It is based on a survey of the cantons. The Confederation itself spoke of a "mixed picture".
Measure justifiable according to the Federal Council
Just over a year ago, the Federal Council brought the ordinance on the temporary increase in electricity production into force. From October 2022 to the end of March 2023, the operators of certain hydropower plants were obliged to reduce the residual water volumes so that more water was available for electricity production. This was intended to strengthen Switzerland's security of supply.
Due to the time limit, the Federal Council considered the impact of this measure on the environment to be justifiable and proportionate compared to the economic benefits. However, the evaluation has now shown that electricity production could be increased to a lesser extent than expected. It increased by a total of 26 gigawatt hours (GWh). An additional production of 150 GWh had been estimated.
Drought had an impact
The federal government sees several reasons for the large difference. For example, some hydropower plants were unable to implement the ordinance for technical reasons. In addition, the foreign authorities would not have supported the measure for power plants in border regions.
Furthermore, the measure was implemented for one month less than planned. Finally, the amount of residual water available in the winter of 2022/2023 was smaller than expected. The drought probably had a negative impact on electricity production in some places.
Negative consequences for fish
According to the study, the reduced residual water volumes had a negative effect on the environment. In 8 out of 15 rivers or streams analyzed, fish reproduction suffered. The endangered river fish nase and grayling were also affected.
However, according to the study, it can be assumed "that biodiversity would only have been irreversibly damaged if the regulation had been applied in the long term". A detailed assessment is not possible based on the available data.
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