Yah...OK...I'm not gonna dump my holding tank in your swimming hole or anyplace without a good tidal flow...but the 3 mile rule is a bit ridiculous just considering how many marine mammals and birds and other species are crapping in the same water. Boaters are literally a drop in the bucket (no pun intended). This is just another example of over-zealous environmentalism. Instead of fixing the real problem...(runoff, over-flowing sewage systems, fertilizer etc.)...find a small defensless group and make them travel 3 miles offshore to dump their tanks since the d+$%$##n pumpout stations are never working or too far away to be of practical use.
Meanwhile...one good rainstorm in the Chesapeake Bay region puts more pollution in the Bay than if every boat there flushed it's tanks today. The caribbean countires have no pump outs at all, large boating populations and the water is safe for all except in a couple of harbors.