Pulling the plug

Today was the open day at Dowley Gap Locks and Aquaduct wher the canal is currently drained for some maintenance work. It was great to see loads of people of all ages walking down through the drained locks and then across the aquaduct. There was lots to photo and it was all very facinating, and the sun shone which made it all the better. I took several shots of the drained locks and people walking along the muddy aquaduct bottom , but this shot stood out for me once I looked at them on the PC. I've never considered the fact that locks have plugs before.