The current of Rhine water offers the possibility to produce energy without polluting the environment and without using up the water. However, hydropower plants, the turbines of which transform the enormous power of impounded water to energy, have many negative impacts on the ecological functions and the continuity of rivers.
Among others, considerable river training measures in the upper reaches of the Rhine, where many reservoirs and barrages have been built and the construction of 21 barrages between the outlet of Lake Constance and Iffezheim restrict fish migration and induce considerable mortality of fish which may be injured during their downstream migration through the turbines (see Technical Report no. 140 of the ICPR concerning Rhine tributaries). Backwaters and the loss of habitats thus induced, in particular in connection with the so-called hydropeaking caused by hydropower plants along smaller watercourses in the Alps, damage the natural development of water bodies.
Furthermore, barrages downstream the weirs entail streambed erosion in the freely flowing section of the river causing the groundwater level to sink together with the river level. This is detrimentally impacting alluvial plains, drinking water production and agriculture. Downstream of the Iffezheim barrage this tendency is being counterbalanced by regularly introducing bed load into the tailwater.
that, as early as the Middle Ages, many watermills in the Rhine watershed used hydropower?
They transformed hydropower to mechanical power in order to grind cereals and silica, to saw wood or to grind ore. However, these mills only worked during daytime, today, the turbines of hydropower plants turn 24 hours a day.