The stream became the main navigation channel when the lock was built in 1790.

A navigation channel and lock were also part of the original facility design.

It is a major navigation channel on the west coast of North America.

Further dredging followed in 2011, to maintain the navigation channel.

The swing bridge over the navigation channel was removed sometime in the early 1970s.

"We want them to do more than just dredge the navigation channels."

Until 1790, the stream was the main navigation channel of the Thames.

The cut creates the only stretch on the river where there are two alternative main navigation channels.

Efforts to maintain and improve the navigation channel have continued to the present day.

"The whirlpools themselves never freeze, and then there's the navigation channel."