Grand Theft Auto: San Andreas Walkthrough

With the team assembled, it's time for CJ to discuss the plan. In order to gain access, CJ needs to shut off the city's power supply.

Head to the airport, marked by a yellow blip on your radar.
Once there, head to the north side of the runway for the waiting jet.
Take off and head to the drop point, marked by a yellow blip on your radar.
Ascend to the proper height and pass through the corona. When you're prompted, hold Y to jump from the plane.
Freefall for awhile, heading toward the red marker in the distance.
Deploy your chute and glide to the drop point.
Several guards block the way down the path. Crouch and sneak your way up the path. A knife is behind one of the containers, marked by a green blip on your radar.
With the guard's back turned, sneak up on him and gut him like a fish.
Another guard waits around the corner. Take him out and continue ahead to the red marker.
Now inside, several generators need to be destroyed.
Sneak up the stairs to the first generator, holding Y to plant the charge.
Follow the pathway to the next generator. Several guards and engineers will be along these paths. Be sure to sneak when approaching them. If you're spotted, the other guards will be alerted.
Plant the charges on the remaining generators, for a total of 5 generators.
Once all of the charges have been planted, head to the exit, marked by a red a marker.
With an attempt to escape on the roof, CJ jumps off the pathway and into the dam, passing the mission.