Background From the 1630s, there was a lot of interest in draining the Fens, to convert them from marsh to agricultural land. In 1638,
King Charles I had appealed for "divers gentlemen, experts in such
adventure, to give their advice, how these lands might be made winter grounds." Among those who responded was the Dutch drainage engineer
Cornelius Vermuyden, who presented the King with a discourse in January 1639. His six-point plan envisaged diverting the
River Welland; building a navigable sluice on the Old
River Nene, below
Stanground; building floodbanks along of Morton's Leam, set back from the channel to allow it to hold flood water; improvements to the River Nene from Guyhim to Wisbech; building bigger and better banks set further back from the Bedford River, a new channel which had recently been completed; and a cut-off drain along the eastern edge of the Fens to take water from the
River Wissey,
River Lark and
River Little Ouse and return it to the
River Great Ouse at Denver. Only some of this was carried out, and the cut-off channel was one of the items which did not get constructed. The issues were probably financial, but all records for the work carried out were destroyed in the
Great Fire of London in 1666, when the Fen Office was burnt down. In the early 1800s, the drainage of the southern fens was still inadequate, and
John Rennie was consulted. Amongst other schemes that he suggested was the construction of a catchwater drain running round the southern and eastern boundaries of the fens, from Stanground on the River Nene to Denver on the Great Ouse. In this case, we know that the issues were financial, since he estimated that it would cost £1,188,189 (equivalent to £ in ) to implement. A series of flood events in 1937 and 1939 required the Great Ouse Catchment Board to consider action. Failure of a bank had caused some flooding in
Soham, but more serious was that water levels in the vast washland between the Great Barrier Banks, either side of the Bedford Rivers, had been higher than the banks, and widespread flooding had only been prevented by continuous lines of sandbags placed on the bank tops. Anticipated failure of the western bank did not take place, saving large areas from being inundated. This was not the case in 1947, when breaches occurred on several banks and some of land in the South Level was underwater. Further north, the Welland flooded near Crowland. In the South Level, many families had to abandon their homes, until teams of army engineers and volunteers were able to repair the damaged banks and pump the water from the land over the next several weeks. Following the 1939 crisis, the Great Ouse Catchment Board, set up under the
Land Drainage Act 1930, employed the civil engineer Sir
Murdoch MacDonald as a consulting engineer, to develop a solution. Discussion continued through the 1940s, and he proposed a cut-off channel, to collect the waters from the Little Ouse, Wissey and Lark, and deliver them to Denver, and a relief channel, running parallel to the Great Ouse for from Denver to
King's Lynn. The route was very similar to that selected by Vermuyden, leaving the River Lark above Mildenhall, rather than below it, but otherwise, much the same. W E Doran, the Chief Engineer for the Great Ouse
River Board, the successor to the
catchment board, stated that "had Vermuyden's original ideas been followed, most of this trouble could have been avoided."
Construction After delays caused by the Second World War, the 1947 floods brought the scheme to the foreground again, and construction of three schemes, the cut-off channel, the relief channel, and improvements to the Great Ouse between Denver and Ely, began in 1954. They were finished by 1964. Around 40 per cent of the water in the Great Ouse is supplied by the three eastern rivers. At about the same time, planners were considering how to resolve water supply problems in Essex, where development and expansion were hampered by a lack of available drinking water supplies. By 1968, a scheme had been designed, that involved reversing the flow on the Cut-off Channel during the summer months. Water is fed into the channel by the sluice at Denver, and flows southwards to Blackdyke Intake, between the River Wissey and the River Little Ouse. From Blackdyke Intake, the water descends down a shaft to a low-level tunnel, at the far end of which is
Kennett Pumping Station, which raises the water to the surface. Pipelines carry it to
Kirtling Green outfall, where it enters Kirtling Brook, a tributary of the
River Stour, to be extracted from the river system further downstream, for pumping to
Abberton Reservoir or
Hanningfield Reservoir. This is known as the Ely-Ouse to Essex Water Transfer Scheme. When work began, it was a joint project between Southend Waterworks Company and South Essex Waterworks Company, but by the time it was completed in 1971, the companies had merged to become Essex Water, and have since become
Essex and Suffolk Water. ==Flora and fauna==