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 or Chittenden Locks during large lock maintenance 003.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.