Our Stream has a set of lock gates on it for lifting and lowering floating discs or boats in the Stream. The technology of canal locks is over two hundred years old - before railways, canals were the only way to move heavy goods around the country. This video explains how they work:

If you’ve used the black gates of the stream to trap and control the flow of water, you may have more in common than you think with nature’s greatest builders. From their iron rich teeth to their powerful tails, the Beaver uses its unique anatomy to create the dams for which they are infamous.