Use the aqueducts and irrigation channels behind the house to make your way to the rendezvous point with Jan.
Mission Objective: Use the aqueducts and irrigation channels behind the house to make your way to the water purification plant.
Locate the grate in the floor and slash it; drop down into the irrigation channel below. Slash the grate up ahead and continue to the end, then fall into the main channel. Continue following the channel until you come upon a large door. Activate the switch to open it, then walk up the slope to the left and jump up out of the channel. Make your way to the channel with water in it.
Secret Area 1/6: Jump into the water and swim along the current to a grate. Cut it to gain access to the secret area.
Swim against the current up into the aqueduct. Follow the water flow and jump out onto the left-hand slope. Work your way to the metal grid and crouch to get through. Follow the empty ditch to the neighboring channel to the left. Jump into the water and let it carry you into the next area. Cut the grate on the way to continue.
As soon as possible, swim to either the left or right bank and get out of the water, then jump onto the catwalk.
Secret Area 2/6: When the path bifurcates, take the right-hand path to the end. Jump into the water, then jump out before you tumble down the waterfall, into the open area across the way. Turn around and jump up one of the sides and up into the secret area.
Take the left-hand path and hop over to the left-hand bank. Jump up onto the nearest bank of the small ditch. Cross over to the right-hand bank and follow it to the end, then look down. Drop into the ditch below to avoid taking damage.
Secret Area 3/6: Instead of riding the water flow, jump out of the ditch at the earliest opportunity; it doesn't matter which side. Jump down to the concrete floor beneath the ditch. Run along the down-sloping floor to the end and drop into the small ditch at the end, then go left into the culvert.
Secret Area 4/6: Drop to the ledge below the area you're in now and enter the room up ahead.
Exit the secret area and follow the ledge to the empty water tank. Drop into the small ditch and then into the empty tank. Jump through the drain in the opposite wall and follow the ditch to the end, where it connects to the metal structure pictured. From the metal beam, jump up onto the left-hand sloped ledge and follow it to the beam up ahead. Bypass the vertical pylon and step back onto the sloped ledge and go through the doorway at the end.
From here, follow the left-hand ledge to the central horizontal beam, then cross it to the other side. Turn to the left and follow the ledge to the doorway at the end.
This is the final section. Stay on the ledge and cross the horizontal beam. Take the right-hand ledge to the end. Get onto the far horizontal beam and fall into the water. The ditch will drop and curve left.
Mission Objective: Find the passage to the river dam.
Secret Area 5/6: Jump out of the ditch and up onto the left-hand bank. Follow the slope down and walk along the edge of the ditch, then drop down into the room below.
Jump back into the water and let it carry you into the purification plant. Swim along the surface of the water while looking down in order to locate the giant square hole in the wall. Swim down through the hole and all the way to the bottom, while circling left around the central structure to the next opening. From there, swim directly up into the plant, surface, and jump out of the water.
Hit the switch to raise the water level, then go back out the way you came. Jump up against the current and up onto the bank. Follow the ditch straight ahead and ride the current to the end. Swim to the bank on the right-hand side and jump up. Follow the path to an elevator and ride it up.
Once there, continue along the path until it branches off to the right, then take the elevator down. Go through the room and to the edge, overlooking the stagnant water channel. Clear out the water cycs (the Bowcaster is most effective for that) and jump into the water.
Secret Area 6/6: There's a pipe at roughly the halfway point along the channel, in the right-hand wall. Swim through it and surface in the room at the end.
Jump out of the water onto the left-hand bank at the very end and walk up the slope to another ditch. Follow it until it emerges outside. Jump up onto one of the sides of the ditch and fall into the water below, then head up the far slope and go through the door.
Note: Don't get too close to the sequencer charges; they can be set off from a safe distance with thermal detonators.
Mission Objective: Beyond the dam is your rendezvous point with Jan.
Ride the elevator to the top and locate the switch on the wall, then ride back down the elevator and go through the now-open door to wait for Jan.