Both sides of the inner harbour are accessible and have parking nearby. The east side also has a beach you could cast from, but is probably better to head out on the break to hit deeper water. It also gives you a choice of casing into the creek or the lake simply by turning around.
To the west of that I can only think of one access that is semi-public.
The east side of the harbour is where I grew up so I know it better, but it has also changed a lot since I moved away. I imagine the outer harbour will have some pan fish and the like. There is good access to all sides along the original pier and the newer breakwall. Parking is on-street, at any of the under-trafficed mall lots, or there is a larger lot available at the outer harbour. From the outer harbour heading out east is a public walk with shore access all the way and a bit beyond to Tulip St. There is a little break wall about half way.
Let us know how it turns out. I'll be heading back their for the first time in years for fishing tomorrow with my son. I've NEVER caught anything there but with some age, success elsewhere and knowledge gained from OFF I hope our luck is different!