It looks like an unused mine tailing pond, but is seems a wierd place for one.
Google link
Terraserver version
but I've not been able to come up with any reference to
any man-made structure in that area. The nearest mine is a few miles away, and, as
far as I can find out, abandoned years ago. There were some parts of the lake bed used for evaporation pits a while back, but they were south of
there, I think.
It might have something to do with the water-rights fights going on in the area (that golf course across the street uses tons of the stuff).
