There's a link on here (somewhere) that describes in detail the changes. I was bored, so I read it, front to back. Pretty interesting stuff actually. Only changing the first section to help the fishies. I don't remember the length, but it's pretty short--less than a mile as I recall, and that's pretty much starting at 470 and going north.
Basically, this section will be narrower, more curvaceous, and include riffles and pools and some other technical term for a bank that I can't remember.