Waste Weir and Holding Pond

Waste Weir and Holding Pond. . A water control structure , The man-made holding pond in front of you helped to maintain the level of the canal when the lock was in operation. The water in this holding pond had two purposes. It helped maintain the water level in the dry summer months and minimized the drop in water level when the lock was being filled. Each time Lock 3 was used, roughly 400,000 litres of water were sent down to the next level of the canal system. Beneath the boardwalk you are standing on is what is known as a waste weir or water control structure which, together with the dam and the lock chamber, form the lock system. The primary purpose of the waste weir was to keep the water level constant at the head of the lock. Excess water from heavy rains or spring runoff was allowed to drain away from the lock through the channel behind you and then on to Lake Micmac. , To maintain the desired water level in the canal, logs in the waste weir were removed or added to by the lock keeper. Similar weirs were required at each of the locks.