If you are putting a seine or dipnet in the Powell be prepared to be stopped. There are explicit reaches and locations in the Clinch and to a lesser extent the Powell River where you cannot wade. Say what you want about game wardens, but in that area, they know their non-game fish and they will question what you are doing, fishing license or scientific permit.
Seperate from this but in the big picture of the subject. Alot of times regulation confusion is self inflicted because of over thinking and dancing on egg shells when it is not warranted. When you want an answer, call the right person and take time to figure out who is that right person beforehand. You won't waste your precious time, which will save you frustration, let alone the person on the other end of the phone. I'll get off my "from the other side of the fence" soap box now.
Also, remember that when most regulations were written, they weren't really thinking about people like us. And when you talk to people, remember that it's really hard for them to know ALL the regulations. I mean, they don't spend most of their time worrying about this very issue - they handle other regulatory issues much more often. One can't have all the regulations memorized. I mean, have you ever tried to read them all? I've read many, and still have to go back to look things up when I'm working on a project.