The Scottish Government’s ambition to decarbonise its electricity generation means that run-of-river hydroelectric power schemes are now a feature of many Scottish catchments. The essential requirements of these schemes (adequate hydraulic head and flow) mean that their locations often coincide with important freshwater habitat. A scheme can have various effects on the quality and extent of this habitat, in and downstream of the depleted reach (between the intake and tailrace), and upstream of the impoundment.