Author: Anne Miller

The Fen Causeway: some background and history

As it will be Fen Causeway’s centenary on 6th December this year, we thought that it was appropriate to provide some background information on its planning and construction.

The Fen Causeway, which links Trumpington Road to Newnham (not to be confused with the Roman Fen Causeway linking Peterborough and Denver across the Fens), was approved in 1923 and completed in 1926.  The aim was to provide an alternative to the Magdalene and Silver Street bridges as a route across the Cam as they were becoming congested as the volume of traffic increased.  It is now part of the Cambridge inner ring road and is heavily used.

The narrow lane to the East, alongside the Leys School, had previously been called Coe Fen Lane and before that Love Lane. Possibly the Love Lane name indicated that it was a popular place for romantic assignations on the edge of town. Obviously the building of the bridge put paid to that!

It appears that traffic congestion had been an issue for a while as there was a previous plan to build a bridge here in 1895 but this was not taken forward.  The Cambridge Collection has a design drawing for this bridge which is in a typically elaborate Victorian style.  Sadly by 1926 building styles had become more functional and less decorative.

The arches in the centre were to enable the flood waters to pass down the apron.

The building of this substantial bridge was strongly opposed by local residents who considered the road would be ugly and spoil the tranquility of Coe Fen and Sheep’s Green. It was only approved after a public enquiry which considered alternative options.

Financing was through a central government Labour creation scheme employing ninety unemployed men.  The labour creation scheme was used during the depression era to help alleviate unemployment.

The Fen Causeway was opened by the mayor of Cambridge, John S Conder on 6^th December 1926. He was a horticultural builder, served as a liberal councillor of Cherry Hinton, and founded Cambridge Housing Society (CHS Group) along with Alex Wood and Dorothy Stephenson

Fen Causeway is now heavily used, and frequently jammed with stationary traffic.

Sheep’s Green and Coe Fen

On the South of Fen Causeway is Sheep’s Green with Coe Fen on the North.  At the Newnham end it is adjacent to Lammas Land.  Incidentally Lammas lands are named after the Lammas festival on August first which celebrated the harvest being brought in.  Lammas rights entitled commoners to “pasture following the harvest, between Lammas day, 12 August to the 6 April” so Lammas lands were common land for 9 months of the year and then were private the rest of the year. Presumably therefore the surrounding area was close to agricultural land. 

Coe Fen and Sheep’s Green were traditionally used for grazing since medieval times. Cows were grazed on Coe Fen and sheep on Sheep’s Green. As part of the Fen Causeway construction a “cattle creep” was included near Robinson Crusoe island.  A cattle creep is a low tunnel for animals to pass from one side of a road to another. 

The name Coe Fen also appears as a hymn tune by Ken Naylor, who taught music at the Ley’s school.  It was written in 1958 for the hymn ‘How shall I sing that majesty’ by John Mason (1646?-1694).      

The Cambridge Collection holds a long poem: The Coe Fen Road by Quentin Nelson with some delightful drawings.  This was possibly published by the Mercury Press in 1929.  I found it in Down Your Street Vol 111 West  Cambridge by Sara Payne.

Coe Fen and Sheep’s Green are now a designated local nature reserve with significant biodiversity. There is a rich bird life with herons, kingfishers and little egrets visiting the reserves.  It is encouraging that the endangered water vole is flourishing and bats (Pipistrelle and Daubenton species) can be seen at night.

It is said that Charles Darwin carried out many beetle surveys in this area.

The land is prone to flooding and there were a number of ancients streams which flowed across the area (as can be seen in the map above).  These channels can be seen in wet periods. The City council will shortly be reinstating them to improve biodiversity.  As mentioned above the bridge construction took account of the possibility of flooding with the inclusion of the central arches.

The River Cam at Sheep’s Green was granted Designated Bathing Water status in May 2024. This was following a campaign by Cam Valley Forum and consolidated a long tradition of bathing (including in the nude) in this area dating back to the 18^th century, especially by university students.

I am very grateful to the Cambridge Collection at the Cambridge Library for finding material to assist me in my research. 

Bruce Huett, Cam Valley Forum

Work continued removing Himalayan Balsam throughout August, helped by the drought. This noticeably restricted the growth of any plants that didn’t actually have their roots in the brook, although at times it made it too hot to work.

Trumpington Farm Company and our contractors had mowed the meadow and some of the wood earlier in the year. This mowing has drastically reduced the number of plants but they continue to emerge from seed, so its important to keep checking and pulling them.

Mike focused on removing emerging plants from the meadow, helped because the mowing had made them much easier to spot.

The Meadow, late July 2026

In parallel with this, Tom, Anne, Michael and Mark focussed on removing plants upstream and downstream of the meadow, and alongside the meadow from a canoe. By 23 August, the whole of “our” stretch had been completed, extending from the footbridge upstream of the M11, downstream to Byron’s Pool, and half way along the leat to Grantchester Mill (where it’s blocked by a fallen tree)

Using a pruning saw from a canoe, upstream of M11

Removing several 100kg of balsam from the brook, downstream of the meadow.

Part way through clearing the Himalayan Balsam from the Leat to Grantchester Mill

Delicate handling needed, when plants are about to spit their seeds

Small heaps of pulled Himalayan Balsam stand out against the brown vegetation.

This map shows the approximate situation on 23 August, after the completing at least one clearance of the whole stretch….. This was a nice milestone, but there will undoubtedly be more plants emerging, especially as we’re now starting to get a bit more rain!

If you would like to help by spending a few hours pulling Himalayan Balsam in this beautiful spot this summer, do signup here, or email us on info@camvalleyforum.uk

You can read about the “Bourn Brook Balsam” project here

People are naturally very concerned when, during a drought and a hosepipe ban, they see pumps operating to abstract water from the River Cam or its chalk stream tributaries. We have had a number of queries about this over this summer, so this blog aims to provide some answers.

Current legislation states that an individual or a business may “abstract” (i.e. remove) up to 20 cubic metres of water a day from a river, stream, lake, or underground source – equivalent to 20,000 litres or 4400 gallons/day, whether that’s from a single place or several different places on the same river or stream. Above that amount, a licence from the Environment Agency is required.

The Environment Agency has acknowledged to us that the current allowances are over-generous and pre-date the current water scarcity situation and that there are intentions to amend the legislation.

As Rob Bakewell, of the Environment Agency, has explained to us:

“Licence specific details will include how much water can be taken, when it can be taken, where it can be taken, and for what purpose. We monitor river water levels and flows via telemetry from sites around East Anglia, including along the River Cam. My team monitor these Monday to Friday and inform licence holders when they can and cannot take water, based on conditions designed to protect river wildlife and habitats. Water levels in the River Cam and its tributaries are currently low due to a dry spring, and some licences have seen temporary reductions in abstraction, but abstraction is currently still permitted. This can change depending on how river levels and flows are affected by weather conditions. Environment Agency teams are currently reviewing and renewing abstraction licences in the area. This is a rolling programme where we review abstraction in our catchments. This includes checking that water use is environmentally sustainable.”

Legislation requires that abstraction licence holders from all sectors must submit annual returns detailing how much water they have taken. The Environment Agency encourages licence holders to do this using their online Water Resources Licensing Service. Returns data are checked to ensure water has been taken according to the licence conditions. Although there have been cases of farms breaching their permits, Rob Bakewell says that in our region nearly all licence holders take water legally and, if any discrepancy is noted, the EA regulatory teams investigate and take appropriate action.

The Environment Agency’s 2020 Cam and Ely Ouse Abstraction Licensing Strategy sets out how abstraction is managed.

If you suspect someone is taking water when they shouldn’t, or to report an environmental problem, please call the Environment Agency’s 24/7 incident hotline on 0800 80 70 60.

Here are two examples of abstraction, that we’ve been asked about

Trumpington Farm Company

Cam Valley Forum has received several queries in relation to a pump that has been operated by Trumpington Farm Company, near a popular spot on Grantchester Meadows, below the Red Lion Pub, Grantchester.

Rob Bakewell of the Environment Agency has explained to us:

“Trumpington Farm Company holds four abstraction licences that allow them to take water from parts of the River Cam, Granta, and Rhee. At this time of year, the company uses the water to irrigate crops. Their licences allow them to move pumps along certain stretches of the rivers, rather than taking water from one fixed location, so pumps may be placed wherever the water is needed. This can mean that other river users may see and hear abstraction pumps operating, as part of normal farming activity.”

We have also discussed this with the Dave Knott, the farm manager for Trumpington Farm Company.  He explained that they have a large network of storage reservoirs, pumps and pipes, and that they also use the rivers to transfer water. Part of this network is shown on the map below.

Their reservoirs near Cantelupe Farm are refilled during wet weather and can hold 32 million gallons of water to use when the weather is dry.  To our surprise they told us that they are currently (in August 2026) pumping this water INTO the river, as a way to transfer it to where it’s needed.  They then pump slightly less back out again, further downstream where they need it to irrigate crops: in this case, near Grantchester (opposite Red Lion meadow).

The water that people have noticed being pumped out of the Cam at this spot is being pumped through a network of pipes up to a field nearer to Trumpington Road, where it is being used to irrigate sugar beet. 

We were reassured to hear that they aim to put 110 litres into the river, for every 100 litres they take out of the river. It seems that Trumpington Farm Company is behaving according to the regulations, and we are pleased that they realise the importance of maintaining and even trying to increase the flow of the Cam during the drought.

They tell us that they try to only operate the pump at night, because that’s a more efficient way to use the water, but sometimes they’ve also needed to operate it during the day. 

This statement may seem puzzling to those who walk along the river, who have observed the pump in operation during much of the daytime throughout June and July. However, the heat really has been exceptional, and is very worrying; Dave Knott, the farm manager, tells us that the sugar beet is really suffering. He says “It looks like it’s been ironed”.  He is also worried about next year’s harvests, as they should have started planting two weeks ago, but the hard and dry ground has prevented this.

Cherry Hinton and the Blacklands Allotments

This year, as in all previous dry and drought years, there have been numerous complaints and queries about the pump that is seen operating frequently, including at night, on the bridge across Cherry Hinton Brook, at the entrance to Blacklands Allotments (at the Daws Lane end of Snakey Path, near Cherry Hinton Hall).   

The Blacklands Allotments, along with the adjacent banks of Cherry Hinton Brook, belong to Peterhouse College. Local residents can rent a plot.  As a ‘riparian’ owner, Peterhouse (through its allotment holders) is allowed to abstract 20,000 litres a day from the brook, without a licence.  However, the allotment holders together must not exceed the total amount of 20,000 litres a day to which Peterhouse is entitled.

For many years (reportedly since the mid-1960s), certain plot holders have used a pump to abstract water into tanks to use by themselves and for other plot holders.  In both 2012 and 2014, the Environment Agency was contacted about this practice and in both cases, following inspection, the plot holders were told there was no objection.  Unlike many council-owned allotments, there are no water pumps or troughs providing water for plot holders to use, and relatively few plot holders appear to have their own rainwater harvesting systems.  Nevertheless, the pump does not send a good message about the vulnerability of Cherry Hinton Brook during the drought; in previous years, sections have indeed dried out and the level is dropping quite rapidly at the moment.

Allotment holders are struggling with this long dry period.  Many have already exhausted their stored water; others have not had the means or resources to install water storage.  

Friends of Cherry Hinton and Coldham’s Brooks (FCHCB) are working with local allotment holders, with the local Council and all involved to increase publicity about the importance of the City’s chalk streams and to encourage allotment holders to minimise their use of brook water wherever possible.  We are also looking at ways of helping plot holders to install water harvesting systems so that in the future they will have better access to stored water, without needing to use the brook.

Sylvia Haslam ScD Cantab. 1934-2026

It is with sadness that we announce the death at the age of 91 of Dr. Sylvia Haslam who was a Life Member and longstanding supporter of the Cam Valley Forum. She will be best known to CVF members as the co-author, in her retirement, with the late fellow CVF member Tina Bone, of their ‘River Friend’ series of books. Details of these can be found here. Various reviews of the series are included on our website here .   The final book in the series, Book 9, was published last year and focuses on the River Cam.

Sylvia was a distinguished botanist who researched aquatic macrophytes, river ecology and fluvial landscapes across Europe. Howard Griffiths, recently retired from the Cambridge Dept. of Plant Sciences, has written admiringly of her extensive work including the landmark 1975 publication (with co-authors C A Sinker and P A Wolseley) of ‘British Water Plants’. He spoke of being taken by Sylvia to the headwaters of the Granta and Rhee ‘searching for Chalk stream macrophytes from which we hoped to characterise Rubisco kinetic properties as a function of their contrasting leaf carbon uptake strategies’. (Rubisco being that vital enzyme that all plants employ to remove carbon dioxide from the environment!)

Dr. Haslam generously left funds to establish a Tripos Part II prize in Plant Ecology when she moved from Cambridge to Somerset to be closer to her family. After a funeral service in Taunton she was buried in the churchyard of St. Andrew and St. Mary, Grantchester in July.

Sylvia expressed her despair at the declining state of rivers, not least the Cam. An inveterate long-hand letter-writer Sylvia was sharp to the end.

DB

Timetable for investments to improve the bathing water quality at Sheep’s Green

Here is our understanding of the current timetable for improvements to the Sewage infrastructure in the Haslingfield area, based on our regular meetings with the Environment Agency and Anglian Water

This investment programme is aiming to improve the water quality from “Poor” to at least “Satisfactory”. It is a direct result of having achieved Designated Bathing Water status for the Cam at Sheep’s Green in May 2024

May 2024-Nov 2024. Bathing Water designation, initial monitoring and classification.

The Environment Agency started monitoring Sheep’s Green for E.coli, resulting (as we expected) in a classification of the Bathing water Quality as “Poor”. This then triggered the requirement for work to improve it.

May 2025-April 2027. Investigations and Source apportionment study

Anglian Water and the Environment Agency are currently carrying out a major investigation into the causes of the poor bathing water quality. This is a major programme of work, for which Anglian Water have budgeted around £500K. Anglian Water are investigating the contribution from their assets (sewage works, pipes, pumping stations etc), while the Environment Agency is also investigating other potential causes, such as from agriculture.  Both have put sensors (data sondes) in the river at various points, which are monitoring the state of the river 24/7 (we analyse some of the results here). The Environment Agency is also continuing to monitor E.coli at Sheep’s Green, weekly during the bathing seasons, and monthly during the rest of the year. (Our commentary on the results from 2024 and 2025 is available here)

We are also contributing our local expertise and data.  In particular we’re concerned about the impact of the unusually high turbidity in the Rhee and Cam (which reduces the natural degradation rate of bacteria by sunlight)

30 April 2027  The “obligation date” for Anglian Water to provide the Environment Agency with a report on results of their investigations into the causes of the poor bathing water quality.

We are calling for the Environment Agency to make this public, once they have received it in April 2027

30 April 2028  The “obligation date”  for Anglian Water have to have completed the improvements to Haslingfield sewage works “identified through the investigation”, including the reduction of storm overflows. We know they are expecting to install significantly bigger storm overflow tanks, but may include other measures too.

Reducing overflows should help significantly, because we are told the area has a problem with ingress of ground water. Currently Haslingfield Sewage Works is overflowing around 25% of the time

31 March 2030. The “obligation date”  for completion of improved phosphate removal at Haslingfield Sewage works. This is not required for bathing water, but very beneficial for the health of the river.

2030-2035.   Completion of other measures.  If (as we hope) the study recommends major improvements such as UV treatment, we are told it may not be possible to complete this before 2030, so it would be done during the AMP9 “Asset Management Plan” budget period (which is 2030-2035) Anglian Water tell us they have budgeted up to £30M for improvements

When will see see improved Bathing Water Quality?

When the improvements are implemented, we hope to see the levels of E.coli improve quite rapidly, particularly in wetter weather. However, as the formal classification is based on the previous 4 years classifications, we are warned that it may take some time before the formal classification improves from “Poor” to at least “Satisfactory”

Cam Valley Forum welcomes first local hosepipe ban in over 30 years, announced by Cambridge Water and Anglian Water. But a long-term sustainable water supply and healthy chalk streams will require much more than hosepipe bans

FOR IMMEDIATE RELEASE 12^th July 2026

The Cam Valley Forum welcomes Cambridge Water’s decision to introduce the first hosepipe ban in more than 30 years, having long campaigned for the company to use this tool in periods of drought [1].

“We have always thought that hosepipe bans would play a useful role, not only to reduce water use but also to raise public awareness of the water crisis” says Michael Goodhart, who leads our water saving team. “However, at Cam Valley Forum’s annual meetings with Cambridge Water, the company previously always made the point that they did not consider such bans to be as effective as other methods of reducing demand.”

In a welcome change of heart, the company now says that hosepipe bans are indeed highly effective and can lower demand by about 5% (or 5 million litres a day).  In recent weeks, during the hot weather, demand has exceeded 112 million litres a day, which is a 30% increase and the equivalent of an extra 300,000 baths every day [2].

As the Environment Agency pointed out earlier this week (9^th July), the series of heatwaves and lack of rain have meant that, throughout England, soils are drier than average and river flows and groundwater levels are declining [3].  Locally, ponds are starting to dry out and our chalk streams are starting to be affected.

The upper reaches of the Little Wilbraham are now dry, with the lower reaches maintained only by Teversham Sewage Works, which has a continuous effluent outflow [4].

Many other water companies have now also introduced hosepipe bans [3], recognising that these will help to ensure that water is available for other key purposes: for drinking and washing, for farmers to grow our food, and for rivers and our internationally important chalk streams, along with their wildlife, to thrive. Every time we turn on the tap, we are taking water from the same chalk aquifer that supplies all these needs.  The wider Cambridge area is particularly susceptible.  Cambridge Water is the only UK company which obtains all its water from an underground aquifer.  The planned Chatteris reservoir, which will mean rainwater and surface run-off can be collected, will not function until the mid-2030s, assuming it is approved.

Cam Valley Forum has every sympathy with local residents who may be incensed by the new regulation, given the negative publicity nationally about the mis-management of water.  Improvements were needed many years ago.  Leakage of pipes still accounts for 14% of total water usage in the Cambridge area [5] and is made worse by the hot weather and climate change which causes clay soils to shrink and pipes to then crack. Cam Valley Forum is urging the public to report leaks immediately to Cambridge Water [6].

We must however recognise how wasteful the British public is when it comes to water use. Cam Valley Forum is encouraging residents to collect and use rainwater wherever possible, recycle waste water (e.g. from washing up and baths), and avoid taking water directly from local chalk streams. Hosepipes can use up to 1,000 litres of water an hour –the same as a family of four uses normally in two days, or around seven full bathtubs [7].

We also want to see businesses, local councils and both universities take a more proactive role in providing technical support, funding and other help to local residents to address the water crisis. Furthermore, plans and proposals for the future development of the city and its surroundings are, at present, running counter to the urgent need for sustainable water management and we will continue to highlight this.  Cambridge Water, local authorities, businesses, farmers and local communities need to work together to improve water resilience and ensure sustainable water management for both us and the rivers and chalk streams that depend on them.

ENDS

For further information: info@camvalleyforum.uk

NOTES

1. Cam Valley Forum’s campaign for hosepipe bans: https://camvalleyforum.uk/wp-content/uploads/2025/06/CVF-water-press-release-June-2025.pdf; https://camvalleyforum.uk/cambridge-water-reject-plea-for-a-hosepipe-ban/
2. https://www.cambridge-water.co.uk/news/cambridge-water-announces-temporary-hosepipe-ban-to-protect-water-supplies-and-local-chalk-streams/
3. https://www.gov.uk/government/publications/dry-weather-and-drought-in-england-2026-summary-reports/dry-weather-and-drought-in-england-2-to-9-july-2026
4. https://www.thewrps.org/post/l-wilbraham-river-dries-up-again
5. E-mail from Cambridge Water in response to a query from Cam Valley Forum
6. https://www.cambridge-water.co.uk/incidents/report-a-leak
7. https://www.cambridge-water.co.uk/household/temporary-hosepipe-ban/temporary-hosepipe-ban-faqs/

Volunteers have been busy, since the contractors last cut the meadow on 26 May

The working party on 5 July was very successful, with 12 participants, half working on foot, the others in a canoe and 3 kayaks.

Cassie, searching for Himalayan Balsam plants beside the meadow

As the maps below show, this has made a major dent in the number of plants, although there is still more to do.

These maps show the approximate location and numbers of plants on 1 July, and then the situation after the working party on 5 July.

In addition to the working party on 5 July, Mike has been coming to the meadow on the south side of the brook weekly since it was mown and cut by the contractors, to remove small balsam plants as they emerge. There are now very few visible Himalayan Balsam plants.

Before the working party, Richard once again had mown the margin of the meadow, to within about a meter or two of the bank. This was a huge help, removing many plants and making the rest much more visible

On 28 June, Tom and Anne had removed several canoe loads, mostly from between the M11 and the Cantalupe Farm bridge. They also spotted and cleared a “new” outgrowth, on the Cam about 100m upstream of Basely Bridge (Apparently this is coming from the marshy area by the Byron’s Pool car park)

On 3rd July Wim and Anne cleared a heavily infested stretch upstream of the TFC footbridge to a point about 100m upstream of the M11. [Reeds now make it hard to do much more, upstream of this point by canoe, until early next year]

There is a bit more to do (on foot) in the woodland on the north side, but its quite tangly and overgrown. Also (from the water) removing it from the reeds on the left bank, at the downstream end of the brook (shown in red on the map above), and upstream of the M11, particularly on the north side.

We’ll be organising some more working parties in July, hoping to remove as much as possible before it starts spitting out its seeds

Its a lovely spot, with crystal clear water, lots of fish, swans, kingfishers (and we’re told that otters have been spotted too) so do join us and help save it from being overwhelmed by Himalayan Balsam.

If you would like to help by spending a few hours pulling Himalayan Balsam in this beautiful spot this summer, do signup here, or email us on info@camvalleyforum.uk

You can read about the “Bourn Brook Balsam” project here

30 years ago the River Rhee at Haslingfield was crystal clear but now its murky grey.   Mike Foley and Anne Miller of Cam Valley Forum think they now know why.

Mike has been monitoring the murkiness (known as turbidity) of the Rhee the source at Ashwell down to Clayhithe at intervals since 2022.   (The Rhee is the branch of the Cam has its source at Ashwell, flows past Haslingfield to join the Granta or “Essex  Cam” near Trumpington)  The most recent results from 22 March 2026 show, as usual, a huge peak in turbidity just a few kilometres downstream of Ashwell. The murkiness of the water then steadily improved downstream, except for a small peak around Barrington/Haslingfield, and by Clayhithe it was once again pretty clear.

Mike says “We are confident that the peak in March 2026 in the upper Rhee is largely due to dredging that took place at Ashwell End from 28 January to about 7 February 2026. The effects are surprisingly persistent, lasting weeks or months and clearly visible far down the Rhee”

“My test result gave a peak turbidity of 100 FNU (NTU) which is shockingly poor.  Visibility was no more than around 20cm”

Mike has recently discussed the problem with the farmer who is now more understanding of the consequences further downriver.  Mike says, “However, we recognise that flood risk is a worry to farmers, and I hope that an alternative option to dredging can be found.”

Stephen Tomkins points out that “Natural Flood Management, which we want to see in the catchment is a huge component of contemporary Environment Agency thinking. The dredging should certainly stop”

In parallel with Mike’s on-the-ground investigations, Anne analysed data from the Environment Agency.

Anne says “I’ve analysed the historic data provided to us by the Environment Agency for the period 1980 – 2008. This shows that this is indeed true that the river has become more murky, particularly in the summer months. Prior to 2008, the Rhee at Haslingfield would often have appeared crystal clear, whereas today the visibility in summer is little more than 50cm.”  

“The Environment Agency’s historical data also shows that upstream, at Tadlow, it wasn’t great, but it started to deteriorate further in the mid-1990s but by 2008 visibility would still have been around 1m. (That corresponds to an NTU of about 10).

“Environment Agency has also put real time monitoring systems in the river in three places, and given open access to the data. These transmit a result once an hour, 24/7, so  I’ve been analysing the data looking for patterns.  They have been extremely useful and we hope they can stay in place a bit longer.

One can see huge peaks in turbidity after the start of upstream dredging in January and February this year.

“But there is also evidence that American Signal Crayfish are active in summer, particularly around Haslingfield and upstream at Malton.  We can see this in the data, because the turbidity is worst in summer nights, when they’re most active, burrowing and foraging in the riverbed.

One can also see their burrows in the riverbank, particularly around Haslingfield.

We wonder if the turbid state of the Rhee is due to an unfortunate combination of four factors: 

1. Repeated dredging and slubbing-out of the upper reaches of the Rhee, aggravated by erosion of the clay riverbank, and field soils washing in from fields.
2. American Signal Crayfish. Initially this sediment may only have had local impact, but by 2011 American Signal Crayfish were frequently observed downstream of Barrington, and since 2018 they have been spreading upstream of Barrington. We suspect that their aggressive burrowing and foraging on the bed of the river is mobilising the fine clay sediment.
3. Modifications to Harston Mill Weir. Since March 2019, there has also been increased riverbed erosion and channel incision between Barrington and Harston, due to the modifications to Harston Mill Weir in March 2019.
4. The Local Geology. The upper Rhee, near its source at Ashwell, and in tributaries such as the Mill River have fine clay soils, and because of dredging and erosion the gault clay has now also become exposed in the riverbed much nearer to Cambridge, for example from Barrington to Harston.

Although it is impossible to change the local geology,  this suggests three aspects to the solution.

• Encourage the upstream famers to stop their dredging activities, and to protect field ditches from silting up.
• Help stabilise the banks by ceasing herbicide use and reducing the shading (that has developed over the years) so vegetation can regrow and bind the soft banks.
• Repair the damage caused by dredging. We understand that the best solution is to add gravel or aggregate, which then reduces further erosion of the stream bed.

These measures should produce a significant improvement in water quality by reducing turbidity.

As EastWestRail are planning to dig a tunnel near Haslingfield and build a bridge over the Rhee near Harston, we hope they can make a significant contribution to the cost of this work.

For further information, read the full report “The Mystery of the Murky Rhee” here https://camvalleyforum.uk/publications/