thumb|right|The Holland Fen pumping station, which pumps water from Clay Dike into the South Forty-Foot Drain
The South Forty-Foot Drain, also known as the Black Sluice Navigation, is the main channel for the land-drainage of the Black Sluice Level in the Lincolnshire Fens. It lies in eastern England between Guthram Gowt and the Black Sluice pumping station on The Haven, at Boston. 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.
The Drain was navigable until 1971, when improvements to the pumping station led to the entrance lock being removed. 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 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.
History
The Lincolnshire Fens are an area of low-lying land which have been subject to flooding and attempts to prevent it for centuries. In medieval times, the Midfen Dyke was built to drain the area, but by 1500, this was regarded less as a drain for the land than as a boundary marker between the Parts of Holland and the Parts of Kesteven, two of the three medieval subdivisions of Lincolnshire which functioned as county councils until their abolition in 1974. The first serious attempt to drain the area to the south west of Boston, now known as the Black Sluice Area but formerly known as the Lindsey Level, was from 1635 to 1638, when the Earl of Lindsey agreed with the Commissioners of Sewers for Lincolnshire to carry out drainage works which would make of land available for agricultural use. The Earl and a group of Adventurers paid for the works, in return for land grants.
The cost of the work was £45,000, and involved the construction of a sluice near Boston, called Skirbeck Sluice, the construction of the first of the South Forty-Foot Drain, from Boston to Great Hale, the construction of two drains from there to Guthram, which were called the Double Twelves, and the construction of the Clay Dyke Drain. and against this background, the (5 Geo. 3. c. 86 ) was obtained which created the Black Sluice Commissioners, giving them power to raise taxes and authority to carry out drainage works. The scheme largely revived the Earl of Lindsey's original scheme.
In 2013, the pumping station flooded as a result of a tidal surge. The three engines dating from 1946 were damaged by water ingress, and were decommissioned. The other two engines were at a higher level, and remained operational, but were by that time nearly 50 years old, and nearing the end of their operational life. Refurbishment of the pumping station was estimated to cost between £15 and £20 million, and so the effectiveness of the station was reviewed. The review showed that it had been used for less than 2 days of every 100 days since it was constructed in 1946, and that the station barely affected the number of properties that might be flooded. By using the adjacent gravity sluice and the lock to discharge water from the South Forty-Foot Drain, better control of water levels could be achieved, and this had been demonstrated during a period of heavy rainfall in spring 2018. Accordingly, the remaining two pumps were decommissioned in October 2018, and the Environment Agency began looking at what to do with the building.
Functions
thumb|left|Black Sluice pumping station at Boston, where the Drain meets The Haven, was decommissioned in 2018.
The South Forty-Foot Drain serves as a district boundary over the length where it runs roughly south to north. South of Donington High Bridge, the Drain separates South Kesteven to the west from South Holland to the east. The boundary then continues southwards along the River Glen. North of Donington, the boundary between the borough of Boston to the east and North Kesteven to the west follows the line of the Drain. 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.
The main job of the Drain is to gather the waters pumped from the Kesteven Fens, the Holland Fens and the Weir Dyke, a soak dike in Bourne North Fen, alongside the Bourne Eau and River Glen, northwards and eastwards to the Black Sluice at Boston, where they are discharged to the tidal waters of The Haven. The Weir Dyke takes its name from a weir in the bank of the Bourne Eau at Tongue End, which was constructed by the Black Sluice Commissioners, to allow water from the Bourne Eau to overflow the bank when excess water could not flow into the River Glen in times of flood. The overfall weir became redundant when the Tongue End pumping station was constructed in 1966. Of these, 21 are situated on the banks of the Drain, and pump directly into it, while one, the Black Hole Drove pumping station, is constructed over the channel, and acts as a boundary between the part of the Drain managed by the Environment Agency, and that managed by the Drainage Board.
Navigation
thumb|right|The new lock at Black Sluice, allowing navigation from The Haven to the Drain
Very few details about navigation on the South Forty-Foot Drain have been recorded. Historically, the Drain had been navigable, and in 1939, it was listed as being navigable for , from Boston to Gutham (sic) Gowt. Boats up to long and wide, with a draught of about could use the waterway as far as Donington Bridge, but above that, the draught decreased to . It was only open to commercial craft, as pleasure craft were expressly prohibited. It is unclear whether there was ever a right of navigation, or whether the Black Sluice Commissioners simply allowed it. The entrance lock was , and most trade was between Boston and Donnington Bridge. The restriction on use for pleasure boating was removed in 1962.
It is not clear when navigation ceased, with Atkins working for the Environment Agency stating that the lock was closed and removed in 1971, while more recent documents from the Environment Agency state that the lock was closed when the Black Sluice pumping station was extended in 1966, as the extension was built over the top of the original lock. 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. The local authorities which were part of the Fens Tourism consortium conducted a feasibility study, and this report was formally adopted as the Fens Waterways Link by the Environment Agency in 2004, with the support of the local authorities, the East Anglian Waterways Association and the Inland Waterways Association.
The scheme involved a total of of waterway, of which would be new cruiseway, while the rest would be existing waterways which could be upgraded or have their access improved. 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.
In 2007 they obtained funding for the link between Boston and Spalding. 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, and was completed in December 2008, with the official opening ceremony being held on 20 March 2009. The lock project formed phase 1 of the scheme, and the cost of £8.5 million was jointly funded by the European Regional Development Fund, the East Midlands Development Agency, and Lincolnshire County Council. The lock is designed to be used for a period either side of high tide, and so there is a rise from the Drain to the Haven. It has conventional mitre gates at one end, but uses rotating sector gates at the tidal end, each one weighing 12.1 tonnes. It is a dual-purpose structure, designed so that it can be used as a sluice to discharge water by gravity when tide levels in The Haven are appropriate.
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. Beyond the bridge, the drain was officially only suitable for canoes and kayaks.
However, eight narrow boats cruised on the waterway at Easter 2009, and although the channel was narrower and not as deep after Donington Bridge, all of them successfully reached Kingston's Bridge, some further on, where the outlets from Dowsby Fen and Gosberton pumping stations provided enough width to turn a boat. Further progress was blocked by scaffolding erected so that the bridge could be re-decked, rather than by lack of water.
The drain has been renamed as the Black Sluice Navigation by the Environment Agency. In order to use the navigation, an Environment Agency licence is required, and as there are no permanent moorings available on the drain, these are available for one day or seven days. This section would involve changes at Black Hole Drove pumping station, which has been built across the drain and hence would prevent navigation.
By late 2011, there were ten different routes under consideration, and an assessment of them was expected to be delivered in spring 2012. Halcrow Group, the engineering consultancy, were responsible for carrying out the assessment, which looked at the benefits that each route might provide, not only for navigation but also for water quality, water resources and habitat for wildlife. The study was expected to provide a short-list of routes, which would then be the subject of further consultation.
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.
By the end of the assessment process for the ten routes, two remained. One was route 1, the original suggestion which used the existing course of the South Forty-Foot Drain for most of its length, while the second was a new route, designated as route 11. Route 11 had become the preferred route by the summer of 2014. It involves widening the South Forty-Foot Drain from Donington to Surfleet, to a point near to the Black Hole Drove pumping station. A new lock would be needed at this location, but would connect to a new channel, rather than to the rest of the drain. It would pass under a new bridge on the A151, and the connection to the River Glen would involve another new lock. An environmental survey of other watercourses near to the route revealed that several provide habitat for nationally important plants and invertebrates.
Precursors
The idea of a link between the South Forty-Foot Drain and the River Nene is not new, as the first plans for such a connection were proposed in 1809. In that year, proposals for a new canal between the Oakham Canal at Oakham and the Stamford Canal at Stamford, which had been discussed in 1785, were revived, as part of a larger plan for a link from Stamford to the River Nene at Peterborough, and a connection from near Market Deeping, where the Stamford Canal rejoined the River Welland, northwards to the South Forty-Foot Drain. 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. The idea was raised again in 1815 and 1828, but no further action was taken.
Route
Water quality
The Environment Agency measure the water quality of the river systems in England. Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad. There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish. Chemical status, which compares the concentrations of various chemicals against known safe concentrations, is rated good or fail. The South Forty-Foot Drain is designated as "heavily modified", which means that the channels have been altered by human activity, and the criteria for this designation are defined by the Water Framework Directive.
The water quality of the South Forty-Foot Drain was as follows in 2019.
{| class="wikitable"
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! Section !! Ecological Status !! Chemical Status !! Length !! Catchment !! Channel
|-
|
|
|
|
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| heavily modified
|}
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. Prior to 2019, there were issues with tributyltin compounds being discharged into the system, which also affected chemical status.
See also
- Canals of Great Britain
- History of the British canal system
- Fens Waterways Link