The Ouse Washes Website

an independent research and information project


Welmore Lake Sluice and Pumping Station


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Introduction

Welmore Lake is not marked on maps, but Welmore Lake Sluice is. The sluice is at the end of the Delph River, at the most northerly and downstream part of the floodwater storage area on the Ouse Washes. It is the only means of discharging ("evacuating" is the official term) flood water from the Washes into the tidal Hundred Foot/New Bedford River. It is accessable by public only by boat or a long walk, the latter being accomplished by me from Salter's Lode. 

As you may have have gathered from my previous pages, heavy rainfall in Bedfordshire can result in more water than the Great Ouse River can carry to the sea without overflowing one of more of its branches. When the river height reaches a certain level at Earith, some 19 miles south-west of Welmore Lake sluice, excess water is diverted automatically into the Old Bedford River, which from Welches Dam becomes the River Delph.

If the Old Bedford/Delph Rivers cannot cope, the waters flow over the rivers eastern banks into the washes. The water then flows through the washes, over the A1101 Welney Wash Road (which the EA calls "Welney Causeway") often making the road impassable, and is held by the sluice until It can be discharged into the tidal Hundred Foot/New Bedford River by gravity through the sluice when levels in the tidal river are low enough to permit the gates to open.

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page last updated
07 October 2012

If visted before, please "refresh" page to see latest version.


Many of the watercourses, sluices and roads in this area have multiple names, or variations in style.
Some (but not necessarly all) alternatives are shown here,


location map 2

washes from Welney to Denver

Background and 1756 Dam

When Vermuyden created the Ouse Washes in 1652 (by cutting the New Bedford River, or Hundred Foot drain, running more or less parallel to his earlier cut, the Old Bedford River, and by so doing creating a flood plain or reservoir between the rivers) the "outlet" for the stored floodwater was via the Old Bedford Sluice at Salter's Lode.

About a 100 years later, a third river, the Delph was cut from Welches Dam runing alongside and to the east of the OBR for several miles then crossing the washes to join the New Bedford (see maps). The OBR was then diverted into the Delph at Welches Dam and barrier banks built on the west side of the Delph, so removing the northern section of the OBR and the northern 2 miles of the original washes from the flood storage area.

Another small river to the west of the OBR was joined to the otherwise redundant northern part of the OBR. Exactly when and why all this was done cannot be said for certain because the records of those days have been lost, but we do know that about 1756 a dam was built at the end of the River Delph to prevent tidal inflows into the Delph and washes from the Hundred Foot River.

According to the Register (Clerk) to the Bedford Level Corporation, Samuel Wells, writing in his 1830 book, Vol 1, page 731,  "The proprietors of the Wash lands were permitted by the corporation ... in 1753 .... to make a dam at Wellmore Lake ... to keep out spring tides .... [and] at the time of high [upstream] floods this dam ... to be cut through ... by opening a space in the centre, sufficient to wear the dam away."

The adverse effect of this was that the the south/eastern bank of the Hundred Foot River, which in its role as the South Level Barrier Bank prevents flooding of thousands of acres of land, had to sustain the force of uncontrolled water from the Delph rushing against it before the flow turned towards Denver. And of course the dam had to be be re-built after each discharge. Wells added "The reader will smile at such a system of drainage." How right he was.

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The 1825 Sluice

So in 1825-26 (during a period of considerable engineering works conducted by the Bedford Level Corporation throughout the Ouse Washes) a sluice was constructed with four sluiceways spanned by masonry arches. Discharge was controlled by timber pointing doors, which closed automatically on high tides to prevent saline water flowing into the Washes from the tidal Hundred Foot/New Bedford River.

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The 1933 Sluice

The 1825 sluice was replaced in 1933 by a larger structure constructed from reinforced concrete and with steel sheet piling for the side walls. There were only two waterway openings through this sluice, but these were bigger and more efficient than the four openings of the original sluice.

The sluice gates themselves were made of steel, with two 7.3m wide vertical lift gates controlling the water level in the River Delph on the Washes side, and two large counter-balanced flap gates on the tidal side.

To avoid the threat from tidal flooding during the building of the 1933 sluice, the structure was positioned on the Washes side (i.e. upstream) of the original sluice. Although this helped the construction work, it had the adverse affect of moving the sluice further away from its outfall into the tidal river resulting in a build up of silt immediately in front of the tidal flap gates when flood water was not being discharged.

Below, the 1933 sluice seen below from the outlet side just prior to demolition in 1999.
The 1933 sluice just before demolition
(Photo courtesy of Tony Smart)
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location map 1

washes from Welmore Lake to Denver


comemorative-stone

EA info sign



1999 Sluice

The current sluice (below and right) officially "the John Martin Sluice at Welmore Lake" but still commonly called Welmore Lake Sluice, was completed in 1999 after two years work by main contractor Jackson Civil Engneering group and various specialist companies at a cost around £3 million and was officially opened by the local MP, Mrs Gillian Shephard, on 18th April 2000.
The 1999 sluice
The sluice has three sets of gates, each with a verticle lift gate on the inlet side (above, viewed from the River Delph) and a mitre gate (tidal flap) at the outlet (below, from the Hundred Foot River).
The 1999 sluice

An engineering report said there was also an "automatic over-pumping facility" and silt jetting equipment to combat a build up of silt which could otherwise hinder the operation of the gates.

The Environment Agency (EA) claimed that the new sluice would provide speedier discharge of floodwaters, so reducing the time the A1101 is impassable. It is generally felt locally that it has not really helped much, a view opposed by the EA. To be fair to the EA, the problems of increasing siltation in the tidal part of the Ouse and rising sea levels, and a restricted budget are unlikely to allow much of an improvement in the future. The EA carried out major review in 2009 and considered a wide range of options, and it remains to be seen what further action they decide to take.

The 1933 sluice was located south of the earlier one, and the current gates are about 70 metres north of the 1933 one, so probably more or less where the 1825 sluice was, at the junction of the River Delph and the Hundred Foot River.


1999 aerial view of old and new sluices
  The works were carried out in the dry inside a 46 metre diameter sheet piled cofferdam using 16 metre long steel piles.
cofferdam
The cofferdam was restrained by two circular reinforced concrete wallings that also acted as access platforms during construction work. The sluice structure contains 3,500 cubic metres of reinforced concrete and is supported on approximately 170, 18 metre long steel H piles.

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1999 Project Manager's Report

The following is from an article that was published in Issue 16 of the Welney News:
"To avoid the threat from tidal flooding during the building of the 1933 sluice, the structure was positioned on the Washes side (i.e. upstream) of the original sluice. Although this helped the construction work, it had the adverse affect of moving the sluice further away from its outfall into the tidal river. The 1933 sluice has served the Environment Agency and its predecessors very well, but a continuing major problem has been the build up of silt immediately in front of the tidal flap gates. This occurred whenever the Washes were dry with no flood water being discharged through the sluice.
ln 1996 the then National Rivers Authority made the decision to replace the 1933 sluice with a larger, modern structure, which was to be located as close as possible to the Hundred Foot River in order to minimise the problem of silt build up in front of the tidal doors. At the same time, the sluice's discharge capacity was increased by 50% to reduce the length of time that flood water remained on the Washes. This was achieved by providing three waterway openings instead of the two previously provided. Construction work started on site in July 1997.

Like its 1933 predecessor, the new sluice uses steel vertical lift gates to control the water level in the River Delph. However, this time tidal ingress of saline water will be prevented by the action of large timber pointing doors, similar in principle to those used in the original 1825 sluice.

It is realised that siltation in front of the tidal doors will continue to be a problem, despite the benefits of positioning the new sluice much closer to the tidal river. To combat this problem and to ensure that the tidal doors can always open whenever flood water inside the Washes has to be evacuated, a purpose built system of high-pressure silt jetting nozzles has been incorporated onto each of the tidal pointing doors. This silt jetting equipment will be operated on a regular basis throughout periods when the sluice is not discharging, so avoiding the build up of silt in front of the pointing doors which has been such a problem with the earlier structures.
In addition to the silt jetting, the new sluice incorporates two separate land drainage pumps, to be used for evacuating the last remaining volume of flood water which cannot be discharged by gravity into the tidal Hundred Foot River. This will enable environmentally beneficial target water levels in the River Delph to be achieved and maintained over the spring and summer seasons, providing there are no high flood flows in the Great Ouse during this period that would cause the flood control sluices at Earith to operate.

The 1933 sluice was demolished during August 1999 and the public footpath over it was officially re-routed across the access bridge over the new sluice. This bridge will be strong enough to carry any size of any heavy duty plant or equipment which may be needed to undertake future maintenance work either in the Ouse Washes or to the structure itself.

The reconstruction of Welmore Lake Sluice was substantially completed in early September 1999 and an official opening ceremony is to take place in April 2000.

P Cowie, Project Manager."
The "target water levels" Mr Cowie refers to are those required to enable inspection and maintenance of the banks, provide grazing (a lucrative venture for the EA) and breeding gounds for birds.

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opening stone

New 2010 pumping station

The pumping facility fitted in 1999 referred to above proved increasingly insufficient and most years portable diesel pumps were needed to assist. After less than 10 years it was decided to replace the pumps with a new electrically powered pumping station situated up stream of the sluice, with a new outlet downstream.

The new facility was officially opened on 28th October 2010 by Mrs Elizabeth Truss, MP for South West Norfolk. Among those attending the ceremony were representatives of the Regional Flood Defence Committee, RSPB, Wildfowl and Wetlands Trust, the Borough Council of Kings Lynn & West Norfolk and the Environment Agency.
Welmore Lake sluice
(Photos courtesy of Peter Cox, March 2011)
Above, the New Bedford/Hundred Foot River, the 3-gate sluice completed in 1999 at the northern end of the River Delph and the 2010 pumped outfall on the right, viewed from the eastern bank of the Hundred Foot. Click photo to see a close up of the new outfall.
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Does it work?  Is it managed properly?


The short answer to the first question is yes it works, and can do so very efficiently. As for the second question, there are many who believe the management and maintainance is sadly lacking.

These are indeed my own early conclusions too (Jan 2013) after carefull study and observation.

The problems caused by the regular, and sometimes lengthy, flooding of the A1101 at Welney have been debated for many years including in the House of Commons. There are many pages devoted to it on The Welney Website - for starters, follow the link on right.

 
Acknowledgements.
Page produced in co-operation with Peter Cox of
The Welney Website

Article by P. Cowie published
in Welney News issue 16.
photo of 1933 sluice from Tony Smart

If you think there are any errors or omissions on this page or would like to comment, please
e-mail me
and your response will be noted where appropriate.

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Related pages on this website
Welches Dam
River Delph
Welney Gate
Pumping Stations Index
Related external websites/pages
Wash Road Floods Overview/Status