Yeah, even old water mills - while the weirs and water supply channels might still stand, the water wheels are long gone, with a few exception not worth replacing by a modern small water turbine generating electricity.

It is simply not economical to exploit this (originally critical) source of power as its is so small in absolute numbers compared to all the necessary maintenance.

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kragen 13 hours ago | parent [-]

A few years back I visited an old water mill called Itaipú. It has forty water wheels still in operation, providing a total of 14 gigawatts peak. At the time I visited, one of the water wheels was providing 95% of Paraguay's electricity, and the other 39 were providing 25% of Brazil's electricity. It turns 50 years old next year. In 02020 its average production was 8.7 gigawatts. They did have to replace one of the water wheels a few years after I visited: https://www.youtube.com/watch?v=thcIrM31tZ4

Brazil uses more electricity now, some 80 gigawatts, so this one water mill only produces about 10% of it now.

It is true that many older water mills are no longer in use, though. Maybe 50 years to you is not old!

	▲	Tossrock 9 hours ago \| parent [-]
		That's a hydroelectric dam, not a water wheel. A water wheel captures mechanical energy directly for eg grain milling, not conversion to electricity via turbine.