Howdy Qwapaw!
I'd recommend
against the out take pond, that flows back into the Willy. We'd have to come n' "fish" you out of there. What's your bait of choice? LOl
However, don't be at all dismayed. There is LOTS of fish-able water. There are nice level paths all over the place; and much of it is even paved. The stretch behind the restaurant is good. That is where ODFW peeps typically stock it. Although, I think stocking is done for now. There are some bass in there too. I'm not real sure about accessibility for your scooter. But, you could call Eugene Parks n' Rec for details.
There is also the "radio tower pond". It is about a 4 acre pond; and it is almost directly behind Autzen. I've only been there once, so am not sure about access for you. It also has 'bows n' bass.
Here is a map:
Map of Eugene, Oregon by MapQuest
This shows where the AB Canal splits off of the Willy, on the Springfield side of the Freeway (Eastgate Woodlands). Then, the canal flows under I-5. It then flows a mile or so, and into the Radio Tower Pond. From there it meanders and goes past the Science Factory; then past the Restaurant. It's into a YUCKY duck pond from there and then into the out flow pond.
You also might want to call the Springfield Parks department too; so you can find out about access at the Eastgate Woodlands park.
Good luck.
P.S. You can PM NWKiller too. He has been all over than place and would be a great resource for ya.