River Boards were set up under the River Boards Act, 1948 and were responsible for land drainage, salmon and freshwater fisheries and prevention of river pollution; functions that had previously (since the Middle Ages) been dealt with separately.
Each river system or group of rivers in England and Wales was brought under the control of a river board and hence their boundaries, in general, did not coincide with local government boundaries. In certain circumstances, river boards were responsible for navigation undertakings.
By the Water Resources Act 1963, 29 River Authorities were created. These were abolished under the Water Act 1973 and were replaced by Regional Water Authorities.
Link to online catalogue of holdings: