Stuck in HL2...

[question]

hey yall im in the part where the chopper was chasing me and after going thru a series of places im what appears to be like a tunnel, however the other side is gated and i dont know what to do... before the gate theres a ladder that takes u either down into the water or up to the top where i dont see anything, also in the other room theres another ladder that also takes you down to another section of the water, with an opening tunnel above the water, however you cant get into it because the waters to shallow

 

[Rocketman9mm]

I think i know where you are. After you defeat all those man-hacks, you need to get up on that ledge, then go to the gated room with all the pipes. you have to work your way down the pipes, near the water line, you should see a valve, turn it and the water level will start to rise. go back into the room where the man-hacks attacked you, go down the ladder past the grated floor and swim through the now submerged tunnel and you'll be on the other side of the grate from where you turned the valve. you'll have to get across the gap in the catwalks where the water is, look down into the water to figure out how to get across from there.