Prof Tom Williamson & his team at the University of East Anglia have just completed a study of the history & status of staithes (landing places) on the Broads. This was paid for by the Broads Authority and should be published by them shortly. The Prof & his team are historians, noit lawyers.
The essence of his report is:
a) The documentation and justification for a staithe varies - some are defined in Enclosure Acts, some merely by custom & practice, but that custom & practice tends to be documented in things like tithe maps and the 1910 Finance Act maps (which were drawn for the Valuation Office)
b) In many cases, a staithe is part of the highway that serves it and is documented as such - often as simply a widening of the highway land where is meets a navigable river.
c) The right to use a piece of land as a staithe - ie the right to tranship goods between highway and navigable water - is independent of the ownership of the land, similar to the right to use a public footpath across someone's land. It can be extinguished by Act of Parliament, or by impracticability e.g closure of the piece of highway serving the staithe or silting up of the watercourse so it is no longer navigable, but otherwise seems to exist in perpetuity.
d) The right however may be restricted e.g. by an Enclosure Act that created the staithe, to certain persons e.g. "residents of the parish" in which the staithe is.
e) In general however, he has been able to find evidence of the existence of a staithe at most, if not all, points where a highway meets a navigable waterway.
He also expects that this will be true across England.
As a historian, not as a lawyer, he is of the opinion that navigable waterways are like highways - "Once a highway, always a highway", which has implications for a large number of rivers across England.
As far as the Broads Authority is concerned, it is likely that what they wanted to know is who owns the staithes (and who is responsible for their upkeep i.e preferably not the BA!), whether there are staithes that can be brought back into use for tourism, and whether there are rights they can exploit to increase the number of temporary moorings across the Broads. (In this regard remember that rights may be restricted to certain classes of people. The BA may not have the answers they were hoping for.) Williamson also commented that people in Norfolk were quite good at "acquiring" bits of land that were not in use, and that some current owners might be quite surprised to find there was a right to tranship goods across parts of their gardens!
From a canoeing viewpoint however, the wider implications of persistence of navigation rights across England ("Once a highway, always a highway") are of interest, although he did point out that that is set to change in 2025, when unregistered rights of way will cease to exist. (Under the CROW Act??)