[2] The levels are formed from tidal deposits and alluvium, which have been recurrently inundated and reclaimed from the Severn Estuary by humans since Roman times.
The Levels have been reclaimed from the sea at different times during the historic period, preserving evidence of patterns of settlement, enclosure and drainage systems.
Settlements became established, linked by droveways such as the Whitewall at Magor, and land was gradually reclaimed for pasture and arable use.
In 1531, Henry VIII set up Courts of Sewers to improve drainage, but without any powers to oblige landowners to carry out work.
In 1828 the Commissioners for Sewers ordered a series of maps of the Caldicot and Wentloog Levels from Thomas Morris, a surveyor based in Newport.
The long title of the Act is "An Act to provide for the commutation of the liability of Landowners in the Levels of the hundreds of Caldicot and Wentlooge in the County of Monmouth to maintain sea walls and other works to provide for the making and maintaining of roads in the said Levels and for other purposes."
[9] In 2012, the IDB was criticised in a report by the Wales Audit Office for overpaying staff, paying for trips abroad for its members, and acting unlawfully on other occasions.