Straining Tower, Lake Vyrnwy - Wales

Approximately 1,000 metres (3,300 ft) from the dam is the reservoir's straining tower. Standing only 30 metres (98 ft) from the shore its purpose is to filter or strain out material in the water with a fine metal mesh, before the water flows along the aqueduct to Liverpool. Its architecture is Gothic and built during the same time as the dam. The tower as a whole is 63 metres (207 ft) tall, 15 metres (49 ft) of which is underwater. The other 48 metres (157 ft) is above water, and is topped with a pointed copper clad roof, which makes it look light green.
(images)(source)