Nehalem

Ran Vernonia to Pittsburg at 4.88 in a Prijon Embudo Creeker, with two friends in Jackson Regal SoT's. I wouldn't run it much lower, all of us were hitting bottom regularly and got hung up multiple times in shallow water.
It's a good run to take friends with no white water experience on, but I would advise that they have some kayak handling experience.
There is 1 large fallen tree blocking the river, you can go right and squeeze under, in higher water, a portage would be needed on the left bank. There is another section further down with a number of fallen logs that require a portage.