The depth would be 3-6' and it would be from 15-20' wide.
I figure it's close to 1,500 yards that you will have to dig. I dug and moved 200 yards on Saturday with my backhoe and 5 yard dumptruck, and that's about as good as it gets for me with what I have. I've had many 100 yard days too, but even at that rate, 1,500 yards is just half a month of easy work.
What are you going to use to dig and move the dirt with?
I think the best thing about a canal would be a bridge over it. Paddling up and down the same canal doesn't have allot of apeal, but a nice walking trail along it and some cool sitting areas sure sounds nice.
Eddie