Now you will have to kill an enemy sniper. He will be hiding inside the second building (#1). Check the first screen if you're having some difficulties finding him. You could also ask your sniper for help, however I'm sure that it won't be necessary. It would be wise to use one of the smaller containers for cover. You should be able to see the third building from here (#2). Just as before, try securing it from a larger distance.
Keep heading west (#1). You should allow your team members to follow you, however you will have to make sure that there's a large distance separating your main character from the rest of the squad. You should be staying close to the left side of the dam, because some of the nearby buildings will provide a much needed cover. You should be able to locate a small area to your right. There are more containers there (#2). Make a stop and save your game.
You will probably notice that enemy troops have appeared near the containers. Enemy soldiers will probably start running to the left, so you shouldn't have any problems killing them with effective headshots (#1). Make sure that they have been killed. Keep going straight. You will come across new buildings very soon (#2).
You should be able to notice two enemy units in the distance (#1). Thankfully, you shouldn't have any problems killing these guys, especially if you plan on leaning out a lot. You could also order your sniper to move to the right. He should hide behind a small pick-up truck (#2).
Keep heading towards the opposite end of the dam. Don't forget that you have to check all upper balconies for additional enemy forces (#1). Thankfully, rebel units probably won't be hiding inside buildings. You should allow your sniper to move forward. Hide him behind a much larger truck (#2). Check the second screen if you're having problems finding this vehicle.
Once you've secured the dam area, you will have to reach one of the northern towers (#1). This object shouldn't be guarded by anyone, but you should still be very careful while trying to reach that location. The rest of the team should stay on the dam. Enter the building (#2).
4a) Place the EMP on the jamming device (You will only have to do one very simple thing here.)
The jamming device is going to be located to your right. You will have to approach it. Press and hold the X key in order to place a charge (#1). You may exit the building (#2). The explosion won't be imminent, so you will have to defend against enemy attacks in the meantime.
4b) Stop the mercenaries from deactivating the detonator (You will have to defend this position against a few waves of enemy attacks. It's not going to be difficult.)
Despite what you might think, you won't have to hide your men inside the nearby buildings. Allow your sniper to stay near the truck. The first group of rebel units is going to appear on your right (#1). Focus all of your efforts on killing them. You will also have to take out a military vehicle (#2). Make sure that you kill the gunner!