We ran both rapids without scouting last year, so my recollections are of my quick trip through these rapids. My guesses on class are just that.....my best guess.
Alder Creek - Class II+ ???? If I remember correctly, there was a pour over type rock on the right. Moderate waves.
Black Creek - Class III ??? - Big pile of rocks in the center of the river. Largest space to run on the left, and this seems to be where most folks run. Well defined tongue leading into some pretty big waves below 2 ft. level. I entered a little left on the tongue and got a nice bounce about halfway down. It looked like entering a bit more right on the tongue might have been better?????
Like I said, these are my memories of a quick trip through these new rapids, so it was kind of a big blur. There are lots videos on You Tube of Black Creek and a few of Alder Creek. My most vivid memory was being sad that Salmon Falls is gone..... a favorite is now buried.