The narrator presents Camp Green Lake's location in a very negative light. He describes it as a "wasteland," indicating just what a desolate, inhospitable place this is, a place where no one would ever go unless they absolutely had to, as Stanley and the other inmates must.
The whole place has an air of decay about it, which mirrors the corrosive effect of the camp on the souls of those forced to work there. The lake has dried up, the once-thriving town that used to be there is deserted, and all the people who once lived there have long since packed up and left. The narrator adds to this bleak picture by referring to the high temperatures and lack of shade in this desert.
All in all, he's setting the scene for the action to follow, giving us some idea as to what Stanley and the other inmates can expect once they set foot inside the unremitting Camp Green Lake.