Not adding much to what others have said, but I did fish the Big Q about 2 weeks ago, before all the rains of the last couple of days. It was very low for most of the length at that time. There is one big hole about a 10-15 minute walk up the trail from the hatchery parking lot, and a few other smaller ones along the way. Most people were fishing the length just above the hatchery by the train bridge. Most people were float fishing, a few chucking spoons or spinners. I tried both and didn't have any luck, and lost a few spoons in the process. Saw a couple of people land some pinks by the bridge, and there were Chinook in there, though mostly holding below the hatchery where it is not legal to fish.
The rains over this weekend hopefully have made it better. It was a busy spot by 10am, as it is so accessible - so I would get there early. Check the regs, there are limits on hook size.