Ham Island

Ham Island is an inhabited man-made island of roughly 50 hectares in the River Thames in Old Windsor in England. It was a mature meander of the Thames until a channel was dug, the New Cut, to build Old Windsor Lock which reduced the navigable distance by two thirds.

The current island was a peninsula partly surrounded by a meander of the Thames until 1822 when the Thames Navigation Commissioners dug a channel of the river across the neck, the New Cut, to build Old Windsor Lock at its downstream end. At the upstream end a weir was constructed across the mainstream of the river, and at the downstream end of the cut the Old Windsor Lock also has a small weir. Accordingly, the distance in navigation was cut to around one third.

Wikipedia