Please have someone who knows anything about hydraulics and/or whitewater rewrite this article. I've been a whitewater rafting guide on the Arkansas River in Colorado and an avid whitewater kayaker for 10 years. In the winter I major in Civil Engineering with an emphasis on open channel hydraulics and three-dimensional modeling.
I kayaked this wave at around 4000 cfs, and yes, it is a class II rapid *cue screaming from corny 80's horror film*. If there isn't a good chance that a canoe will flip over in a playwave, then it is a really crappy playwave. Out of the few man-made playwaves in Texas, this is definitely the best. The hydraulics caused by the confluence currents after the first wave are the most aggressive part and I assure you that they are the same hydraulic feature that appear behind any bridge column.
Would I wear a pfd (life jacket) if I were canoeing this? absolutely, but I also use a pfd on lake livingston. The fact that anyone would consider this rapid is any more dangerous than is necessary to create a playwave is ridiculous. Saying this playwave "is a disaster waiting to happen" is equivalent to saying the welcome mat on your front door is a deathtrap because someone could trip.
One thing that no one really brought up so far that I've seen is that the playwave is actually good for the environment. The COD levels in this section of the trinity are high because it's in the middle of the city, this playwave continuously raises the DO levels. English: the playwave provides more oxygen for the fish which is a big deal here.