I hear CasperMike is in Texas for the next day or so....
The release is only happening this week. Tonight will be the last time the park will have water at high levels for the next month or so. They release from Gray Reef in the morning and it takes until 3 or 4 pm to hit the whitewater park. It's pretty cool to see the river go from 500 to 3500 cfs in two hours. Here's a link to the release.
The park is good at 3500cfs. The first feature has a nice friendly wave that allows smaller blunts, backstabs, donkey flips, and the occasional "helix" or "felix" depending upon how well you throw them. It's not as steep or fast or as high as south canyon wave (for reference) but you could fit three boaters on it.
I would say it's not worth boating at under 700 cfs unless you are really jonesin. The bottom hole is only good for surfs, spins, and low angle cartwheels at that level.