So .... let me understand this correctly : If some kids go wading, and "disturb" the muddy/sandy bottom of a creek, with their splashing around and wading, then: They need a "permit" , eh ? I don't think so. Nor do I consider md'ing to be "disturbing" any worse than the mere act of wading there, or dragging your fishing lure through mud that stirred up the bottom, etc....
I think that "disturb" thing is no doubt for larger scale stuff, and was never meant to be applied to innocuous things like what we do.
Because, so too does parks , for example, have rules that forbid "disturbing" (or "altering", etc...) . Yet no one assumes that means md'ing, as long as he's leaving no damage, then presto, he has not "disturbED" anything, now has he ? I highly doubt anyone is patrolling creeks and concluding "oh me oh my, that md'r is 'disturbing' the creek bottom "