I used to fish there a bunch, and if you search the archives there should be a few reports, but this year things have seemed much less desirable down there than even just a year ago.
Long story short it's a tough area to fish, but I've caught plenty of bass, pikeminnow, and perch from the few access points there are. You've already seen the boat launch and under the bridge, if you follow the trail that goes down stream you can fish rock creek around the small bridge which crosses it. If you cross that bridge you quickly come back to the Tualatin where the sewage plant dumps into it, it looks nasty but they say it's clean, and I've caught plenty of fish from there.
The river up here is supposed to be closed to bait but outside of myself every angler I've encountered is using worms. I won't condone it, but I won't condemn it either as there's no shortage of warm-water invasives to be taken in this stretch with it.