There was a tide gate here from very early times, separating the tidal Bow Creek from the semi-tidal Bow River section of the Lee. A proper lock was built in 1850, duplicated in 1930. At high tide, as seen here, the tide from Bow Creek used to flow through Bow Locks and raised the Bow River, the Limehouse Cut, and part of the Bow Back Rivers above their maintained level. During the second half of 2000 these locks were modified to keep the tide out and so cut down the former heavy siltation in the semi-tidal section. (See separate pictures.)