A frantic real estate agent calls you from his car phone. He had just returned from an exclusive vacation area where he handles a number of properties. It had been about a year since he had any clients interested in seeing one of the homes on the small lake which was situated near the end of the subdivision, so he hadn't seen the area for quite a while. As he and his client approached the lake, they were both shocked at what they saw. There was algae everywhere and an objectionable odor emanated from the lake shore. Several dead trout were seem floating near by. Needless to say, the client was no longer interested in buying the property. The real estate agent wants to hire you to figure out what has caused this beautiful lake to become so foul!