I have done this trip many times, with many people. There are a couple ways to go. The easiest way is to take a car and drop it off at the Bay, at the parking area across from Bay Creek. Then take a car up to Ellison, put in and float on down.
The harder way is to start at the Bay, paddle upstream. It's fairly easy going until you get up to around Atlantic/Browncroft. There the current picks up and you will be paddling against the current. Most of the time it isn't that bad, but ther are places you'll need to be more than a casual paddler to keep from drifting back downstream.
The wildlife along this trip is amazing. Bring a camera. I've seen swans, geese, ducks, turtles, snakes, red-winged blackbirds, blue herons, kingfishers, turkey vultures and even the bald eagles while paddling up through here.