Detergents that contain no contaminants aren't "refuse" or "pollutants" ("biodegradable" does NOT mean it doesn't contain any pollutants...it only means the pollutants in it will eventually biodegrade.). And besides, "refuse" is garbage and trash. not sewage...and they don't mention sewage, only refuse. They can't legislate against birds pooping or dirt, pollen etc in in the air that lands on your boat...So that shouldn't rule out washing your boat OR peeing over the side.

HOWEVER...anything is enforceable until/unless it's successfully challenged in court...and that's both time consuming and expensive, so few people want to do it. Which how many "illegal" laws continue to be enforced.