Simple Solution: Holding tank with no over board release outlet, i.e. evacuation by pump-out only! That's what we have. Make that mandatory and there cannot be effluent released into waters. Period!
Ta heck with blue die!
Not exactly practical for those of us who venture offshore. We have Headhunter MSD Treatment Systems.
Still we are fine with the restrictions at marinas or in close harbors and would have no issue with the dyes. Not discharging doesn't create a problem for us in those situations. It's on long runs and offshore runs we need to discharge. Also, even though we could legally discharge untreated when more than 3 miles out, we don't choose to do so. Similarly we don't choose to dump bottles or cans. We compact them and dispose of them when we reach shore.