2015 large lock maintenance, Hiram M. Chittenden Locks, Seattle, Washington. At left (not visible here, but see Chittenden Locks during large lock maintenance 001.jpg) is what would normally be considered the lower (seaward) gate of the locks; this is a further gate, mitred in the opposite direction, which provides the seal for pump-out. One hard-hatted worker can be seen in the corner. To his left is one of the entrances to the tunnels through which water enters and leaves the locks.