2015 large lock maintenance, Hiram M. Chittenden Locks, Seattle, Washington. Looking west in the south-side penstock tunnel by which water would normally enter and leave the lock. This is near the east (upstream) end of the tunnel, where it slopes strongly downward to let water in from the fresh-water side. Chittenden Locks during large lock maintenance 058 - in the tunnel.jpg, Chittenden Locks during large lock maintenance 056 - in the tunnel.jpg, and Chittenden Locks during large lock maintenance 060 - in the tunnel.jpg all have the camera in the same position and are shot at different exposures.