There certainly is a range of opinions on this issue, as one might expect, considering the sensitivity of the topic, the size of the ocean, the restrictive nature of some waterways, and the expected differences of point of view.
With these differences, it's necessary to realize that there will be those who dump, so long as it's legal, and probably a few who will anyway until they get caught or are forced to re-plumb their boats so that overboard dumping would be impossible.
Thus if you feel that dumping should be more restricted, at least in certain areas, the only solution is to seek tighter regulations and enforcement.
Here in Shasta Lake, a resevoir, and admittedly a more sensitive body of water to health concerns, the U.S. Forrest Service has sequentially tightened regulations until the following prevail:
1. No discharge of black or grey water is permitted, anytime,, anywhere.
2. All black and grey water must be disposed of through a pumpout station, which all marinas must provide to their customers.
3. All boats using the lake with USFS Permits (31 ft and over) must have their water disposal systems modified so that all waste water is held in holding tanks for pump out.
4. Overboard discharge tubes and vents must be permanently blocked through plumbing modifications. (My larger boat has had this done.)
This approach might seem too radical for open ocean or limited size waterway application, but dumping by some will continue until government regulations and enforcement force those who don't believe there's any problem to put the plug in the hole.
I'm usually not one to suggest more government involvement, but in some areas like this, voluntary compliance will not result in too much change in the status quo.
It's too bad there isn't some easy middle ground in this, but that's the way things are now with fairly open regulations and pretty much voluntary compliance, considering the difficulty of enforcing anti-dumping regulations because of the vastness of the area to be supervised.*
I honesty wouldn't be pleased with such radical changes, but where can we find some practical agreed upon middle ground?
Realistically, it's a big world out there, and we'll never stop the cruise ships and others from dumping in international waters, but we can have some control over our near home waters, particularly those waterways in front of our homes and others that need special protection.
Some obviously don't see any problem, others definiely do!
* grey water coluld be excepted from tighter regulation in many areas.
Joe.