Anywhere in the USA inside of the three nautical mile line discharge of untreated sewage is prohibited.
Further to that there are isolated areas that prohibit discharge of treated sewage.
The solution is a mandatory holding tank with frequent trips to
pump out, or stay in a place with a
pump out
boat.
Or use a sewage treatment system with a small holding tank for use when you’re in a no-discharge zone.
Or use a composter.