Clause 33 of the Magna Carta of 1225
All kydells shall be removed from all rivers
It is argued that this only applied to the 'Great Rivers' of England - Thames, Severn, Humber, Ouse. The clauses of Magna Carta have anyway since been repealed.
Evidence does exist that shows Navigation of other rivers - e.g. in Sussex
The king against clark.
Information for building locks on the river Thames. An information was filed against Clark for building of locks on the river Thames, to the obstruction of navigation. And per Holt, Chief Justice, to hinder the course of a navigable river is against Magna Charta,
A comment on the Magna Carta from Song of the Paddle