Finally something i know something about! My wife does enviromental studies, i can't say what kind or who for, hope you understand. There are many things to consider when using a stream or river. Freind of a friend touched on a real touchy subject up in wash. state, watersheds. They are everywhere and aren't posted with the green and blue sign. Enviromental impact studies are done where there is fish,wetlands,algea,birds, ducks , and geese, etc. These studies are done first by scouts that work for parks and wildlife. These are for proposed highways, housing development, wildlife refuges, etc. All this you can look up in your local p&w website for your state, different laws vary but i can tell you this, All water is owned by something unless it's an ocean,sea, and sometimes even a gulf. If it runs through someones property they have rights to it up till their property boundries, unless wetlands or some damn fish is discovered and then the state takes over your portion of water and a chunk of surrounding area for preservation of some fish or algea you never heard of or care about. If it freeflows like the size of the river it belongs to the state for whatever reason they see fit, usaually prospected bridge sites for higway congestion ease, unless a fungus is descovered then they move up/down stream in SEARCH