All the buildings throws me off. In one area it looks like a landfill, but just a short distance away are large towers and what appears to be an enclosed conveyor - like that used at a cement plant or an asphalt plant. However, I didn't notice any scale house where trucks would weigh in and weight out. I did see a bulldozer and an excavator in an area just below and to the left of the polygon, but nowhere is any place dug deep like they would when scraping and digging for fill. Everything seems to be quite shallow.
As far as the lake goes, there are a couple of spots where it appears to be large pipes for either drawing water from or for discharging something into the lake. One such pipe is coming from a fairly small building - a pump house perhaps? There aren't really any vehicles parked around the lake to suggest people are using it for fishing. It could be a waste water treatment plant, since it was said it was to the south of a city, but it seems to be an awful long way away from the city to pump sewage to the plant, but it is still feasible. @Pastor_Ruth is probably right about the coloration of the water being due to the drought and the difference in water depth.
But still, the number of large buildings still throws me off. They don't need that many buildings in a cement plant, stone quarry, waste water treatment plant, or even an asphalt plant. Hmmm.... I'll be thinking about this whenever I manage to pull myself away from my laptop and get to bed. It's already 3:10AM and I have to be up before 8AM.