These boundary rules are subject to change often. Surveyor’s dealing with these boundaries should stay well informed on the laws regarding Riparian boundaries.
I didn’t understand the definition of Riparian or Littoral.
In most cases the high water mark is the boundary for private land owning along shore line’s lakes river or other bodies of navigational water. In some instances the low water mark can also be used.
For the land owned by government the general rule is the boundary is the shoreline.