Channelsea River

From the Wikipedia page

Channelsea River is a tidal river in London, England, one of the Bow Back Rivers that flow into the Bow Creek part of the River Lea, which in turn flows into the River Thames.

In 1957–8, the Channelsea River was culverted between Stratford High Street and Lett Road.

In 1994, the historian Dan Cruickshank discovered 4,000 tons (60%) of the lost Euston Arch buried in the bed of the River Lea at the Channelsea River and the Prescott Channel.

Channelsea Island is located on this river.