Cut-off Channel

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 12 miles (19 km) 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.[1] 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,[2] 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.[3]

In the early 1800s, the drainage of the southern fens was still inadequate, and John Rennie was consulted.[4] 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 £89,692,160 in 2021) to implement.[5]

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 the fact 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 58 square miles (150 km²) of land in the South Level was underwater. Further north, the Welland flooded 31 square miles (80 km²) 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.[6]

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 10.5 miles (16.9 km) from Denver to King's Lynn.[2] 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."[7]

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.[8] 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 90 feet (27 m) down a shaft to a low-level tunnel, at the far end of which is Kennett Pumping Station, which raises the water 280 feet (85 m) 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.[8] 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.[9]