That grassy field is owned by West Penn Power. If you decide to go there, I recommend not driving back on the grass and dirt. Because it is getting badly rutted.
Instead, just before Commercial Street goes over the rr tracks, and just before the rutted dirt track, take a hard left onto an old gravel/asphalt road that goes alongside a chainlink fence, towards Spring Creek.
This old road deadends near Spring Creek and you can park there. From there it is a short walk in the upstream direction (south) to the grassy field.
I've parked and fished and walked through that area so many times from 1987 up to the present, and no one ever told me to leave, and it's never been posted against trespassing.
Either the park or this grassy field should be good options.