There is a nice one up Memaloose Creek a short way. Just past the water intake area. The rest of the waterfalls on the SF Clackamas require hiking/wading up the creek above the big waterfall. There is a 30' waterfall less than a mile upstream and then another one probably another half mile above that.

Is the one on Memaloose the one right next to the tunnel?  If so, we could hear it but not see it.  I'd like to try and bushwhack down to get a good look at it.  There was also one that had a HUGE logjam at the top of it which was pretty cool.

I'm wondering if it would be easier to go downstream from Hillockburn to see the other two falls on the South Fork?

I'm not sure which tunnel you are talking about. There is an old bridge on your way upstream, cross the bridge and continue up until the road falls apart. There is an old aquaduct inlet there. The waterfall is just upstream around a bit of a corner from there. You can also bushwack down from the road above it. The waterfall is a sweet 30' into a small pool, it then turns to the right 90deg. and falls/slides down another 50' or so. The canyon is quite steep around here but it is possible to hike around the falls.

As far as the SF, I think it is easier to go up from the bottom although it probably doesn't make that much difference. Hiking around the first 30' falls above the big one on the lower section requires some rock climbing skills although you can do it without a rope. The other falls is easier to get around.

I have hiked down to the first big falls on the south fork from the hillockburn trail many times.  It is probably a mile or so to reach it, and I have always waited until late in the summer when it is warm enough and the water low enough to just wade and rock hop in the creek.  I take my fishing pole and always end up having a hoot of a good time.