The area is bounded on the northwest and east by the River Nene and Ouse washes, on the north by previously drained Marshland silts and to the south and west by low clay hills.

The Middle Level river system consists of over 120 miles (190 km) of watercourses most of which are statutory navigations and has a catchment of over 170,000 acres (690 km2).

[2] The fen area gradually became separated from the sea by extensive sand banks, which circled the fringes of the Wash.

[3] During the Roman occupation, some embankments were erected to protect agricultural land from inundation by rivers and sea water, but when they left in 406, the Fens became a wilderness of marshes and flooding again.

[5] The last stand against the Norman invaders took place in the region, and ended in defeat when Hereward the Wake was betrayed by the monks of Ely in 1071.

They found it difficult to fund any kind of drainage works, as the population were unwilling to pay for them, but around 1400, the commissioners were given powers to raise taxes and punish those who refused to contribute.

[8] The Wars of the Roses interrupted his plans for further land drainage projects, and the Dissolution of the Monasteries between 1536 and 1539 had a catastrophic effect on the region.

Monasteries had supervised many land drainage initiatives, but once they were replaced by hundreds of small landowners, there was neither the resources nor the organisation to maintain the works, which rapidly fell into disrepair.

The project was the inspiration of Sir John Popham, the Lord Chief Justice, who assembled a team of associates to complete the work, all of whom would benefit from it.

There were, however, still major problems with flooding in the Fens, and several commissions were held in the early seventeenth century to investigate what could be done.

[10] Finally, in 1630, Francis Russell, 4th Earl of Bedford assembled a group of 13 other Adventurers, and with the approval of King Charles I, embarked on a grand project to turn all of the Great Level of the Fens into agricultural land.

The scheme was declared complete by a Session of Sewers, which met on 12 October 1637 at St Ives, but the following wet winter showed that there were serious flaws in its execution.

The corporation's general objectives remained unchanged but its powers in respect of navigation rights and taxation were much improved.

[16] The Middle Level suffered from the fact that the Nene flowed through it, and its outfall at Salters Lode was restricted by a sluice.

[18] Drainage of the Middle Levels remained difficult, and rival schemes to divert the water through Wisbech and King's Lynn were proposed from 1836 onwards.

As well as powers to raise more rates, the commissioners also received an annual payment from the Bedford Level Corporation, who no longer had to maintain Tongs Drain.

The "rates" on non-agricultural properties, such as houses and factories, are paid through a special levy issued to the district councils within the Commissioners' area.

In addition, Middle Level staff also undertake engineering and planning liaison consultancy work for a large number of Boards.