Google seems to think you can walk across the river to this park... How do I get here from the other side of the river?

This is a google maps fail the same thing happened to me. You'll either have to take the ferry (which is NOT where google maps sends you), or drive over via the I-5 south bridge or the one near Oregon City. I got there by using an address for a farm next to the east side of the park.

Lol no. It didn't take me to a ferry. It took me to some person's house.

The Canby Ferry is right there, I think it's $4 one way