When the Domesday book was produced in 1086, the Ouse valley was probably a tidal inlet with a string of settlements located at its margins. In later centuries the river was draining the valley sufficiently well for some of the marshland to be reclaimed, by building embankments to create highly prized meadow land. However, by the 14th century the Ouse valley was regularly flooding in winter, and frequently the waters remained on the lower meadows through the summer. In 1422 a Commission of Sewers was appointed to restore the banks and drainage between the coast and Fletching, around inland, which may indicate that the Ouse was affected by the same storm that devastated the Netherlands in the St Elizabeth's flood of 1421. Drainage became so bad that of the Archbishop of Canterbury's meadow at Southerham were converted into a permanent fishery (the Brodewater) in the mid-15th century, and by the 1530s the entire Lewes and Laughton Levels comprising over , were reduced to marshland again.