A study of a few years ago reported that the chief source of enteric bacteria in Southern California coastal waters was bird (suspect gulls) poop.
They were wrong. Sewer pipes from land are the principal source. Among other things they're too short, leaking, in total disrepair...etc. Although Catalina Island is too far from the mainland ("26 miles across the sea") to be coastal waters, Avalon was designated "dirtiest harbor in the US" a couple of years ago because 99% of the island's sewage lands in it untreated. But it's not the only one on either coast to have land based sewer system issues. 100+ municipal sewer systems on the east coast in such disrepair or so antiquated or have been made so inadequate by population growth that they've been allowed to continue operating via a waiver from EPA.
But let one li'l ol' boat dump a 10 gallon holding tank, or worse yet flush a marine toilet directly overboard, and the enviro-zealots go berzerk!
Probably okay. I don't think there are any coast guard regs about direct discharge.
True. There is none.
If you're referring to "direct deposit" from a human into the water from above it or while in it, that's correct: there are none. But put it into, or let it pass through ANY container--even a coffee cup--on its way into the water, and you can run afoul of a whole bunch of USCG regs...iow, "bucket and chuck it"
ain't legal.
Hope all of you are enjoying great Thanksgiving holiday!
--Peggie