The Drain has its origins in the 1630s, when the first scheme to make the Fen land available for agriculture was carried out by the Earl of Lindsey, and has been steadily improved since then.

Water drained from the land entered The Haven by gravity at certain states of the tide until 1946, when the Black Sluice pumping station was commissioned.

It is currently being upgraded to navigable status by the Environment Agency, as part of the Fens Waterways Link, with a new entrance lock being completed in December 2008, giving access to the first 12 miles (19 km) of the drain, and the upgrading of the southern section, including a link to the River Glen to allow navigation to Spalding forming phase 2 of the project.

The Earl of Lindsey's contract with the Commissioners of Sewers was revoked by parliament, and it was another hundred years before the next attempt to drain the area.

[1] Much of the area to the south and west of Boston, some 91 square miles (240 km2), was inundated by the Great Flood of 1763,[4] and against this background, the Black Sluice Drainage Act 1765 (5 Geo.

was obtained which created the Black Sluice Commissioners, giving them power to raise taxes and authority to carry out drainage works.

Some of the surveying was performed by John Landen, who was the steward of the estate of Earl Fitzwilliam at Peterborough, and a proficient amateur mathematician.

The two men were jointly appointed Surveyors of the Works, acting as engineers for the scheme, while John Chapman and Richard Strattard were assistants.

A historian called W. H. Wheeler, who chronicled the Lincolnshire fens, wrote that "the works were efficiently carried out and, being well-designed, entirely answered expectation.

Maps of the area produced in 1783 by Edward Hare show 46 such mills, which provided drainage for 32,000 acres (130 km2) of agricultural land.

Ten years later, a map covering 18,000 acres (73 km2) of the Black Sluice area showed nine steam-powered and eight wind-powered drainage engines in use.

As the Drain crosses the line of the Midfen Dyke, just before the Nottingham to Boston railway joins it at Great Hale pumping station, the boundary turns northwards, following its medieval course.

[17] Subsequently, the East Anglian Waterways Association promoted the idea that the Drain could again be made navigable as part of a larger scheme to improve leisure facilities.

When completed, it would connect the Rivers Witham, Glen, Welland, Nene and Great Ouse, and was heralded as the biggest waterway enhancement project in Europe by the Environment Agency.

Work on a new lock beside the Black Sluice pumping station at Boston - to connect The Haven and the South Forty-Foot Drain - was formally started on 8 February 2008,[20] and was completed in December 2008, with the official opening ceremony being held on 20 March 2009.

[23] The upper limit of navigation was initially Donington High Bridge, where the Swaton Eau joins the South Forty-Foot Drain and provides a wider section where boats can be turned.

[21] Phase 2 of the Fens Waterway project involves the link between Donington Bridge and Crowland and Cowbit Washes, which are located on the River Welland near Spalding.

[21] The initial technical assessment and obtaining of planning permission for phase 2, which involved widening of the South Forty-Foot Drain from Donington to a new road crossing under the A151, a new lock and a junction with the River Glen at Guthram Gowt was funded by the East Midlands Development Agency.

[26] This section would involve changes at Black Hole Drove pumping station, which has been built across the drain and hence would prevent navigation.

[18] Major contracts for this phase were expected to be awarded in April 2009,[21] but appraisal of the technical assessment revealed that more than one route needed to be considered before the best solution could be selected.

While the obvious solution would be to connect the Glen and the drain where they are only a short distance apart, the Lincolnshire Waterways Partnership also considered the creation of new channels up to 9.3 miles (15.0 km) long to form the link.

In the meantime, the economic situation changed, so that sources of funding were not so freely available, and by the end of 2010, no clear dates had been set for the next construction phase.

[28] By mid-2012, the merits of the ten routes had been considered, including the economic, environmental and technical issues involved, and a broad outline of the corridor for the link was scheduled to be published in September.

After that, consultation with landowners and stakeholders took place, to establish the final route, for which design of the channel and the associated locks, bridges, moorings and pumping stations could then begin.

It involves widening the South Forty-Foot Drain from Donington to Surfleet, to a point near to the Black Hole Drove pumping station.

An environmental survey of other watercourses near to the route revealed that several provide habitat for nationally important plants and invertebrates.

A bill for this, together with one for a rival scheme to link Stamford to the Grand Junction Canal, which also included a connection to the South Forty-Foot Drain, were put before Parliament in 1811, but neither met with any success.

Reasons for the water quality being less than good include physical modification of the channel, which prevents the free movement of fish and other organisms along the waterway, discharge from sewage treatment works, and runoff from agricultural land.

Like most waterways in the UK, the chemical status was rated as fail in 2019, due to the presence of polybrominated diphenyl ethers (PBDE) and mercury compounds, neither of which had previously been included in the assessment.