First of all, what is happening in California at the moment is a tragedy. Lets hope that it everything will sort itself out ASAP.
After looking at the Amtrak website, it looks as though the status of the Portland, Oregon to San Diego, California train is fine. If you want to make doubly sure however, I would call 1-800-USA-RAIL (1-800-872-7245) and make an enquiry about your specific trip you are taking.