The forerunners of today’s IDB’s date back to the time of Henry III who established a Commission for drainage of Romney Marsh in Kent in 1252. Most IDB’s today were established by the Government following the passing of the Land Drainage Act 1930.
The Upper & Lower Medway Internal Drainage Boards were set up in 1934 following a public inquiry held by the Minister of Agriculture and Fisheries because there had been several appeals against the proposed inclusion of certain areas in the initial Internal Drainage Districts. As a result of that inquiry the Minster set out various principles incorporated in what became known throughout the country as the “Medway Letter”.
Areas of benefit were defined as those areas included in a contour line 8 ft above highest known flood level in non-tidal areas and 5 ft above high tide in coastal areas. These became the Upper & Lower Medway Internal Drainage Districts.
The Upper Medway Internal Drainage District is non-tidal; its downstream boundary being Allington Lock sluice which separates the tidal length of the River Medway from the non-tidal. The 8 ft above highest known flood level contour definition within the “Medway Letter” limits the Internal Drainage District to the lowlands and, in fact, of the total Medway catchment of 340,966 acres only 34,379 acres are lowland, roughly 10% sit within the Upper Medway Internal Drainage District.