The Upper Witham IDB is an English Internal Drainage Board responsible for land drainage and the management of flood risk for an area to the west of the Lincolnshire city of Lincoln, broadly following the valleys of the upper River Witham, the River Till and the course of the Fossdyke Navigation.

Land to the west and south of Lincoln was regularly inundated by flood events occurring on the River Trent.

[1] Wheeler suggests that the normal course of the Witham in dryer weather was into Brayford Mere, a large lake to the west of Lincoln, and then westwards, roughly following the course of the Fossdyke Navigation to reach the Trent.

To the east of Lincoln, the Langworth River flowed into another mere, located between Washingborough and Chapel Hill, and on to the sea near Boston.

The preamble stated that there had been a good navigation along this route for centuries, but that both the Witham and the Fossdyke had become clogged with silt.

The flood waters remained for 3 weeks, and it took 80 loads of faggots and over 400 tons of earth to repair the breach in the river wall.

[5] The Act stated that it was For embanking, draining and improving certain Lands in the City of Lincoln and County thereof and in the parishes or townships of Boultham, Skellingthorpe, Saxilby, Broxholme, North Carlton, South Carlton, Burton and Hathow in the County of Lincoln and for inclosing Lands in the said parish of Skellingthorpe.

[7] At that time, all discharge was by gravity, and the main outfall for both districts was through a tunnel under the River Witham at Coulson Road.

[7] By the mid-1920s, the government realised that the existing laws concerning land drainage were in disarray, with much of it still depending on Henry VIII's Statue of Sewers of 1531.

The four IDBs have a common Chief Executive and Director of Operations, and a number of financial and administrative functions are also shared.

Under flood conditions, levels in the main drains rose rapidly, and internal pumps had to be stopped at the time when they were needed most.