you require a low level endorsement and permission of landholders. As for national parks, landing is banned. Most water authorities ban landing on storages without permission and that would no doubt include river banks. CASA regulations state that permission is required. You don’t have it automatically. Hence everything is forbidden unless you gain a one off exemption.
Every fiber of CASA reflects this basic principle: everything is prohibited except under certain conditions.
That is why all the rules are written: “A pilot commits an offense................(insert action
) .................unless................”. Everything is forbidden unless it’s compulsory.