it is simply that there is no choice. In the lake, and eventually, in the Gulf, it will be gradually diluted. Many of the chemicals end up in the gulf anyway, though not so high concentrations all at once. Much of the sewage IS a temporary problem, as it is not being treated first. Experts could tell you the precise answers to this, and no doubt are hard at work figuring it out right now. Careful searching on Google could no doubt get relevant answers....but I'm not sure I want to know.