The canal broke.
The water rushed in, displacing the masses already huddled in terror from their benefactors.
On this red letter day, one wrong turn leads you to…
The Flooded District
An area of City 17 where the combine's expansive destruction has broken through the city's canal, flooding a low-lying section of the city and even further displacing some of the city's downtrodden. But the Overwatch still has a presence here, and Gordon needs to get back on track towards Black Mesa East.

Developer Notes
Inspired by the identically-titled Dishonored chapter, I think this environment and water-damaged aesthetic could offer some interesting gameplay for Half-Life, even after all that water the game has seen. I'm going to try my best to keep up with this, though it would be unsurprising if it fell behind amongst my many other personal projects. We'll see!