Intermittently working hydropower plants create a periodic change of the water regime of the water body concerned, leading to a very short term change from high water discharge to very low water regime. These sudden and completely unnatural water level fluctuations may considerably impact on water bodies by:
- Reducing the stock of fish and macrozoobenthos species
- Reducing biomass of fish and macrozoobenthos.
- Altering the species composition of macrozoobenthos and fish.
- Increasing drift and running aground of water organisms (among others juvenile fish)
- Largely causing a biological desertation of the zone of changing water levels, as biological adaptation to short term drying up and subsequent flooding is not possible.
From a point of view of water ecology, the ICPR believes hydropeaking to be detrimental to waters and requires the implementation of measures alleviating hydropeaking (e.g. more regular regime, slow down the reduction of water discharge).