Llangynidr Locks
There are Six Locks on the Monmouthshire-Brecon Canal with one lock at Brynich and five Locks at Llangynidr. 

The "out of season" period is an ideal opportunity for upkeep or repair on the locks or canal bed and a section of the canal is drained to enable the necessary work. During January 2104, the Canal Trust changed a lock gate at the Depot Lock. This was quite an occasion with open days where groups of visitors to could actually enter the lock and receive a short history from a member of the Canal Trust. Television cameras were there to record this momentous event. 

The Locks are used to move a boat from one level to another and are filled and emptied using 'paddles' which let  water through the gates or surrounding stonework. The Boat "crew" use a windlass (a special handle) to operate the gear that controls these paddles. Many a careless crew member has dropped the windlass into the lock and during the canal drainage there are always a few to be retrieved!. At many bridges and narrow sections of the canal there are grooves on either side of the canal. Wooden planks aptly named Stop Planks are dropped vertically into these slots to isolate a length of the canal so it can be drained for maintenance work. The planks are often stacked nearby when not in use.

For extra information the following link is to a short history of the Locks and pond