actually that "dirty water" is just really shallow water, you're seeing the bottom. its only about a foot deep there and it extends out quite a ways. The story behind that island is that it is a man made island. all the junk they dig up when dredging channels they used to dump there. it belongs to the DOD (Department of Defence). they don't dump on it anymore and it is now a boating hot spot.
yes, the water is DIRTY though, there is a ring arround my boat after every jobbie nooner. mostly from the exhaust on the boats (the usually vent out into the water if you didn't know already). so, a wash for the boat and a shower for yourself are always a good idea afterwards.
and if you think that theres a lot of boats there, thats was 3 years ago and it has grown every year.