Is there long term parking at the station?

I checked the rates last week. It would be cheaper to park at PDX, then take max, uber, lyft or cab to Union Station

I would be driving into Portland from California to go to Pasco. I want a safe place to park for a few days. I need to investigate other Amtrak stops that might be safer.

Small lot across the street, parking structure a block away

Yes, but it's a hefty fee.

I'm not for sure you might want to ask call and ask them