Something doesn't add up here for me. A grate over the spillpipe? One that would prevent fry from escaping, in addition to adult fish? And still allow water to discharge without plugging up constantly?
Never heard of that, and I would be interested in reading the regs also.
Of course I would never stock a fish that the DNR considered invasive, or illegal in my state, in the first place. Sounds like a good way to land yourself in hot water.