Temporary Closure of Baits Bite and Jesus Green Locks

Cam Conservators have just informed us (21/5/24) that due to safety concerns regarding the structural integrity of the lock islands at Baits Bite and Jesus Green, the decision has been taken to temporarily close the locks until further notice. More detailed structural investigations will be undertaken and a plan for remedial works developed urgently. The Conservators are engaging with the Environment Agency and Local Authorities to seek a coordinated approach.

This applies to all boats, and the footways are closed to pedestrians and cycles. Any boats currently between Jesus Lock and Baits Bite Lock that want to travel elsewhere cannot do so by water…..

More information here

Celebrating Bathing Water Designation

On 19 May, we gathered to celebrate achieving Bathing Water Designation for the River Cam at Sheep’s Green, together with cake and an optional swim.

As you can see in the short video below, for some swimmers, the water temperature was quite a challenge!

The Environment Agency will now be testing the water quality weekly during the bathing water season, and you can see their results here

The initial water quality is very likely to be classified as “Poor”, which should in turn result in around £5M of investment to clean up Haslingfield Sewage works upstream. By 2028, we should have cleaner water in the River Cam.

More information about Bathing Water Designation, and the benefits we expect here.

What happens after Bathing Water Designation?

Now that the River Cam at Sheep’s Green has become “Designated Bathing Water” the Environment Agency will start by monitoring the water quality every week during the bathing season to decide its official initial classification.

The bathing water season starts on 15 May, and on 14 May, the first “pre-season” test result for Sheeps Green was available on the Swiminfo website page for Sheep’s Green.

Both the E.Coli and the IE result would indicate “poor” water quality. This webpage explains how the Environment Agency interprets the results, but at simple level, an E.Coli reading of above 1000 is “considered elevated” and if continued would be likely to indicate a possible overall “poor” rating for the season.

When the City Council’s official bathing water signage is available it will include a QR code to the Sheep’s Green page of the swiminfo website so that swimmers can judge if they wish to swim. In the meantime we’ve provided a simple poster with the QR code at Sheep’s Green and other key spots, giving a link to these official test results as they’re released.

In future years, the City Council will put up an official signboard at Sheep’s Green informing people about the Bathing Water Quality, based on the test results from the previous year(s).   

We know from our own monitoring work over the last few years that the level of faecal indicator bacteria in the River Cam means that this initial classification will almost certainly be “Poor”, with “Bathing not advised” (although of course it’s still permitted)

Importantly, when there is Designated Bathing Water with a “Poor” water quality classification, this then acts as a statutory “Driver” requiring the water company to investigate the source of pollution and remedy it.

Anglian Water have confirmed to us that if the River Cam becomes “Designated Bathing Water” they will start by doing a “Source Apportionment” study to understand and uncover the causes of the problem. This will include looking at both their various assets (pipes, pumping stations and sewage works) and other 3rd party sources.

As Cam Valley Forum we will be very interested in the results of this Source Apportionment study.

We all expect that a big source of the problem will be the ageing and overloaded sewage infrastructure at Haslingfield.

Subject to the findings of the Source Apportionment study and approval of Anglian Water’s Business Plan by Ofwat they’re expecting to spend around £5M on improvements at Haslingfield, with work completed by 2027. The details of what needs to be done, will of course depend on what the source apportionment study discovers, but the overall aim is to improve the water quality in the River Cam at Sheep’s Green from Poor to Good

Without the statutory “Driver” of Bathing Water Designation, the improvements would have been likely to take much longer…. probably decades.

It’s going to take a while, but now we have got Bathing Water Designation, a cleaner Cam is within our grasp.

Bathing Water Designation: Success!

Cam Valley Forum is delighted that the River Cam at Sheep’s Green has received Bathing Water Designation, alongside 26 other sites across the country.

Cam Valley Forum has been working towards this since 2020, and our application was supported by a wide range of local organisations, from the local Women’s Institute to Cambridge Canoe Club, Cambridge City Council and South Cambs District Council, as well as 93% of over 500 respondents to the consultation.

This is because it is a practical way to help protect the health of local swimmers and those punting, kayaking, canoeing, rowing and paddleboarding on the river.

Jean Perraton, a former Chair of Cam Valley Forum said “When I saw what the river group at Ilkley had done, in getting bathing water designation for the River Wharfe in 2020, I thought why don’t we do it too.. I’m so pleased at last it’s succeeded”

Anne Miller of Cam Valley Forum says “Given our dysfunctional water regulation system, this is one of the few effective tools we have to help clean up the River Cam.  Now that the River Cam has been designated as Bathing Water, the Environment Agency will provide swimmers with weekly information on the cleanliness of the water, and there will be the investigations and investment to reduce the sewage pollution at source

Michael Goodhart has a special affection for Sheep’s Green, as it is where he learned to swim in the 1960s. He says that “for 150 years, between 1820s and 1970s, this was the much-loved Town Bathing Place. I am delighted that Sheep’s Green is again recognised as a Designated Bathing Place.”

Local swimmer, Simon Crowhurst says “This is great news for the wildlife and plants in and around the river, and for everyone who enjoys swimming in the river Cam. At last the river water quality should be properly monitored, and eventually improved.”

Why does Bathing Water Designation help?

Bathing Water Designation was designed by the EU as a powerful mechanism to help protect the health of swimmers.

Designation makes it safer for swimmers, firstly, because Designated Bathing Water sites receive weekly monitoring for faecal bacteria by the Environment Agency during each Bathing Season (15 May – 31 September). The results are published on the national Swiminfo website (https://environment.data.gov.uk/bwq/profiles/ ) typically within a few days. This shines a spotlight on poor water quality and will help us all decide if we want to swim in the River Cam.

Secondly, after the first season’s monitoring, the water quality will receive an official classification, which will be displayed by the City Council on a noticeboard at Sheep’s Green. 

Thirdly, because the water quality here will almost certainly be rated as “Poor” it will impose statutory obligation on industry to investigate and reduce the faecal pollution. Cam Valley Forum’s work suggests that a major source is the aging and overloaded sewage infrastructure in the Haslingfield area.. Assuming this is confirmed by the official “apportionment study” the improvements in the Haslingfield area will benefit all of the river downstream of Haslingfield.  This includes the popular swimming spots Grantchester Meadows, Newnham Riverbank Club and Sheep’s Green.

Anne Miller says “ Bathing Water Designation doesn’t solve all problems and it will take a few years to see the results, but we know that the water industry takes Bathing Water Designation seriously. Yorkshire Water have just completed a massive £15M new sewer as a result of the River Wharfe receiving Bathing Water designation in 2020, so we hope to see similar investment and improvements here”.   More information about the Yorkshire Water project and photos here

We know that in October 2024 Anglian Water put around £5M in the budget for investigations and improvements at Haslingfield sewage treatment works, subject to the River Cam receiving Bathing Water Designation.

This will be welcome, even though we will probably have to wait until the end of 2027 to see an improvement in the water quality.

We are keen to see Anglian Water incorporate nature based treatment processes where possible, for example wetlands, rain gardens, swales and ponds, because these will both reduce the impact of wet weather, and create new habitats.

£5 Million is welcome, but we question whether it will be sufficient to upgrade the ageing and overloaded sewage infrastructure at Haslingfield.  Our recently released report “Sewage Sleuthing” shows that the problems are not confined to the sewage treatment works: the pressurised rising main from Haslingfield village to the sewage treatment works burst 3 times in 2022, and the pumping stations in Harston and Haslingfield were overwhelmed 6 times in 2021 and 4 times in 2023, releasing dilute sewage into the streets.

Note that despite speculation to the contrary, the City Council has confirmed several times that there is no requirement or intention to promote ‘Bathing’ at Sheep’s Green, nor to increase facilities.  Designation is not expected to make much difference to visitor numbers, and Paradise Nature Reserve should be unaffected.

It is simply a practical way to help protect the health of existing swimmers and other river users, young and old.

FAQ answering popular misconceptions about Bathing Water Designation at Sheep’s Green here

Nitrates in Cambridge’s Drinking Water

An email is going round to local election candidates about the level of nitrates in Cambridge Drinking water. This asks “What is the position of your party (Lab, Lib, Con, Green, respectively) on the high levels of nitrates in Cambridge drinking water?  Levels around are 50mg/L and unacceptable in any country in the world, never mind in a high tech city like Cambridge.”

We have been asked our view, and are sharing this here in the interests of political neutrality.

In summary, Cambridge Water Company (CWC) nitrate concentrations are higher than in some areas of the UK, because of the source of our supply, which is mainly the aquifer. However, even the maximum results from sampling of drinking water samples are well below the UK and WHO limit of 50 mg/l.  It’s loose talk to state that Cambridge levels are “around 50mg/l” and because of that are unacceptable.

The UK’s Drinking Water Inspectorate explains that “Drinking water extracted from rivers and boreholes in agricultural areas often contain nitrates. Very high amounts of nitrate in drinking water can cause methaemoglobinaemia (blue baby syndrome) in very young children. This is a potentially fatal illness where nitrate is converted to nitrite in the infant’s gut and interferes with the absorption of oxygen by the blood. This extremely unusual illness only occurs when nitrate intake is very high. The last recorded case in the UK occurred in the 1950s and was associated with the use of a shallow private well. However, cases still continue in other parts of the world where there is little or no management of water supplies. The first legal standard for nitrate was set in 1980 and the current drinking water standard is 50 mg/L. The UK standard is based on the World Health Organisation’s guideline value for drinking water, which is also 50 mg/L. This level is intended as a safeguard against methaemoglobinaemia.”

As CWC’s main supply is the aquifers, and this is an agricultural region, and as the aquifers have high concs of nitrate leaching down from soils, CWC’s supply source will also have high levels.  CWC maintains nitrate well below the directorate threshold of 50mg/l.  It has four nitrate-reducing plants for very high nitrate sources, and it mixes and blends appropriately. Results of testing for 2022 are on the Cambridge Water Company website here at 

Cambridge Zone 1 (north city) 39.741.4143.70
Cambridge Zone 2 (south city)37.741.1243.10
Anglian Water at Grafham village (2023)23.431.0240.28
Contrasts with Exeter3.716.8110.86

All values are nitrate (NO3) in mg/l

In contrast to Cambridge, where over 90% of our water comes from the chalk aquifer, in Exeter, over 90% of the water comes from lakes and reservoirs, for example on Exmoor and Bodmin moor. This is why Exeter has such low levels of Nitrates. Although Anglian Water also uses reservoirs for a proportion of their supply, the water sources here generally have much higher levels of nitrate than in the South West.

The calcium in Cambridge drinking water makes its health benefits much much greater than in those areas of acid water like Exmoor. Cambridge water also tastes better!

Note that the UK standard of 50 mg/l nitrate can also be expressed as 11.3 mg/l nitrate-nitrogen.  In the USA, the Environment Protection Agency standard is slightly lower, at 10mg/l, expressed as nitrate-nitrogen.    Some American reporting incorrectly states that the standard is 10mg/l nitrate, which will cause confusion to UK readers trawling the web.

In summary, nitrate concentrations in CWC supply are higher than in some areas of the UK, because of the source of its supply.  However, even the maximum results from sampling of drinking water samples are well below 50 mg/l.  It’s loose talk to state that Cambridge levels are “around 50mg/l” and because of that are unacceptable.

Dramatic increase in Sewage spills into River Cam

The recently released data on sewage overflows shows a shocking increase in the reported discharges from Cambridge City and Haslingfield Sewage Works.

During 2023, the aging and overloaded sewage works at Haslingfield, 5km upstream from Cambridge was spilling sewage for 3000 hours, in other words for 34% of the year.  Cambridge Sewage Works, just downstream of the city, was spilling sewage into the river where our boat race crews train, for 17% of the year.

As the graph below shows, both were dramatic increases from previous years.

We have asked Anglian Water what is going on

Their website says

Our EDM monitors and investments are helping reduce spills and have moved the dial in the right direction. Spills would have been considerably higher without it. However, it is important to acknowledge the exceptionally wet weather we had in 2023, particularly late in the period, which meant that 70% of our spills were in Q4 alone and in stark comparison to the extremely dry year in 2021, as climate change continues to result in more extreme weather events.”

On 9 April 2024, they informed us that at Haslingfield “the EDM point (ie the sensors that detect a spill) was modified a year ago in an attempt to reduce impacts from standing water whilst ensuring that we did not miss spills.  However, it has become apparent that following prolonged periods of wet weather that standing water can rise to reach this probe, therefore further modifications are being assessed”    

When Cam Valley Forum visited Haslingfield sewage treatment works in 2022 we were shown these sensors, which had been relocated from their previous position in September 2021. Subsidence had meant that in the previous position they were sitting in a puddle, rather than recording spills. It’s disappointing if they’re still not correctly positioned to give meaningful results.

It is true that late 2023 was wet, but to assess how exceptional this is, we have looked at the Met Office weather data for Cambridge, which has been monitored at NIAB (the National Institute for Agricultural Botany) every year since 1959.

The rainfall data shows that in 2023 Cambridge was a little wetter than the previous few years, but there only seems to be a vague relationship between the annual rainfall and the duration of sewage overflows during the year. 

The slightly higher rainfall in 2023 in comparison to 2020 doesn’t seem sufficient to explain the dramatic increase in sewage spills. So what’s going on?

The Met Office rainfall data for Cambridge, shows that March and October 2023 were both very wet, which might have been expected to create problems. But these 2 wet months can’t excuse Haslingfield Sewage works spilling sewage for 34% of the year.

Water companies are allowed to spill sewage into the river when conditions are “exceptionally” wet, but the definition of “exceptional” is unclear.

Looking back over the last 65 years, months as wet as the wettest months in 2023 have happened at intervals, but were they “exceptional” enough to make it legally permitted for Anglian Water to spill sewage into the River Cam?  We’ll leave that question for the lawyers to answer. 

However, as the longterm graphs show, Climate Change is making weather that was once “exceptional” seem “normal” so our water companies need to be urgently upgrading the infrastructure to cope.   This applies both to our sewage infrastructure, which in Cambridge is the responsibility of Anglian Water, and fresh water supply, which is the responsibility of Cambridge Water.

Cambridge’s wettest months seem to be becoming more frequent and wetter, and the rate of increase might itself be increasing. (In the graphs above and below, the longterm trendlines are shown by red dashes)

Winter rain doesn’t eliminate the risk of the summer pain from drought.

The same NIAB dataset shows that the average monthly temperature in Cambridge has risen by about 3C since the 1990s.  Winter temperatures have increased even more dramatically: they are now around 6C higher than during the freezing cold winters of the 1980s. This is probably mainly due to climate change, but Cambridge’s increasing urbanisation may be contributing slightly.

These changes increase the risk of drought and of plant pests surviving the winter, while significantly changing our natural habitats and the species that can live here.

They also increase people’s desire to swim in the river, which is another reason why we want our water companies to make the necessary investments so that sewage spills become truly “exceptional” events.

Underlying everything is the growing threat from climate change, so we all need to take urgent action to reduce our contribution to the problem by cutting our carbon emissions. Unless we do, no amount of investment will be able to prevent the horrific consequences.

10 top tips for saving water

To help save our chalk streams:

  1. Go to www.cambridge-water.co.uk/saving-water and join GetWaterFit, the interactive on-line tool that provides advice and from which you can order free water-saving products.  If your water supply is not metered, apply to have a free smart meter installed.  This gives an incentive to save water and is likely to save you about £150 pa on water charges.
  2. Don’t flush every time you pee- ‘If it’s yellow let it mellow, if it’s brown flush it down!’  Reduce the quantity of water used by WC cisterns.  If you have dual flush, use the lesser flush whenever appropriate.  If not, put a hippo in your cistern:  https://www.hippo-the-watersaver.co.uk/.
  3. Fit aerators to taps. These add tiny soft bubbles that reduce the flow of water by about half while maintaining the water pressure, they can be fitted to most taps and are inexpensive.  The water feels nicer and soaks better. https://www.bestproductsreviews.co.uk/tap-aerators .  Taps that provide boiling water will also save water because they can give water of any desired temperature instantly.  These are available from www.quooker.co.uk.
  4. Have brief showers instead of baths.  https://www.bestproductsreviews.co.uk/water-saving-shower-head has an excellent choice of shower heads that use much less water and by aerating the water to give a better soaking shower.
  5. Only turn on taps as far as needed for the task, the full flow is often unnecessary.  Don’t run the tap when brushing teeth. Use a bowl when washing veg or washing-up by hand.  Then, instead of pouring the water down the drain, water plants with it
  6. Washing machines can use more than 100 litres on some programmes and dishwashers more than 20 litres. When buying new appliances select water efficient ones and use Eco programmes.  Wait until appliances are nearly full before setting them to go.
  7. Install water butts with drain downpipe connectors and water plants with rainwater. If necessary during dry spells refill water butts with water recycled, for example from baths or showers
  8. Take prompt action to have any leaky appliances in the house, such as dripping taps or cisterns, repaired or replaced.  Report any leaking water mains to the Cambridge Water Company on 01223 706050.
  9. Engage in consultations with organisations such as schools and businesses and encourage them to monitor and reduce their water consumption.
  10. Assuming a hosepipe ban is not in place, please use your hosepipes sparingly.  Aim the hose at the base of plants most in need of water, and water them in early morning or evenings when water will soak into the ground rather than evaporating into the air.

FAQs about Bathing Water Designation at Sheep’s Green

How does designation help clean up the river?

Designation is a powerful tool to accelerate the cleanup of the river. Firstly, because it shines an official spotlight on the water quality. Secondly, because the water quality here will almost certainly be rated as “poor” it imposes Statutory Obligations on industry to reduce the pollution from sewage works, urban sewage overflows and agricultural slurry.  Unlike general non-statutory calls to reduce pollution, the water industry responds to these Statutory Obligations, so this prioritises and drives real change.   Some of the key pieces of legislation are the ‘Bathing Water Regulations 2013’ , WINEP, which governs the water industry funding and WISER (Water Industry Strategic Environmental Requirements) As explained here, following designation, Ofwat are likely to require the work to be completed by 2027. Without the statutory “Driver” of Bathing Water Designation, Anglian Water could take as long as they liked, so the improvements would be likely to take much longer…. maybe decades.

Designation helps accelerate the cleanup, but we’ll need to keep up the pressure for wider change too. Ultimately, we need to change our relationship with the natural world, so water can be good quality everywhere. However, this will probably take decades and the whole farming and water management system will need to change.

I’ve heard that areas with Designated Bathing Water status MUST promote bathing in the area, which will increase the number of visitor. Is this true

No. This is completely false

The rumour probably results from the line in the Bathing Water Regulations 2013

3.—(1) Part 1 of Schedule 2 lists the surface waters that have been identified in England, other than excluded pools and waters, at which the Secretary of State expects a large number of people to bathe, having regard in particular to past trends and any infrastructure or facilities provided, or other measures taken, to promote bathing at those waters.”

We are informed that this means that it is a site that existing bathers use, with no signage prohibiting swimming, and where there are pre-existing facilities or infrastructure, such as steps, that support bathing.

We’ve also had confirmation from Clean River Ilkley that designation is not about marketing, and does not increase the number of visitors

Will designation increase the numbers of people coming to Sheep’s Green and the nearby Paradise Local Nature Reserve? 

In the short term, no. We are counting “bathers” this summer, and we qualify for designation. (Defra require an average of over 100/ day on the 2 busiest days, and we counted 237 on 10 August and 184 on 19 August and 478 on 10 September)

We know the water quality on the Cam is very likely to be rated as “poor” which will require the council to put up a sign saying “Bathing is not advised”. This will deter rather than encourage swimmers. The experience of other river groups, such as at Ilkley in Yorkshire, is that designation has made no difference to numbers.

However, 3-5 years time, hopefully the water quality downstream from Haslingfield Sewage Works will have improved (something we’ve all been campaigning for).  More people are then likely to feel safe enough to swim in the Cam at Byron’s Pool, Grantchester Meadows and Sheep’s Green.  

We welcome more people connecting with nature, particularly in our highly unequal city.

When considering the Sheep’s Green area, it’s important to remember that the vast majority of the people that come to the area, do so to access the Lammas Land paddling pool, playground, cafe and local walks. When we counted visitors to Lammas Land and Sheeps Green on 19 August 3:40pm-3:55pm, only 2% were swimming in the river. This means that even if the number of wild swimmers at Sheep’s Green does ultimately increase, it will make very little difference to the overall numbers in the area.

Why choose Sheep’s Green, when most people swim at Grantchester Meadows?

Defra only allow applications from inland sites if there are toilets within 500m, and if it’s a short stretch of less than 500m.  This ruled out applying for Grantchester Meadows.  Nevertheless, designation will benefit the whole river between Haslingfield and Cambridge, and people will remain free to swim anywhere.

I’ve heard the council wants it to become a “Destination”. Won’t this increase numbers?

This rumour is based on a misunderstanding. It may have come from the section of the city council motion on 20 July that ‘affirms the goal …of having the water management plan for our chalk streams based on being an ‘environmental destination’ with subsequent protection as sites of Special Scientific Interest (SSSI)”. 

Note that in water resource management government jargon, an “environmental destination” means a “long term goal”, not a “destination” in the tourism sense of the word.  The council motion is about getting a higher level of protection for the chalk streams from abstraction, which is something we very much welcome.

Cllr Katie Thornburrow has confirmed that the City Council has NO plans to turn Sheep’s Green into a vistor destination, and none have been discussed

I’ve heard the council will have to build showers and changing rooms and dredge the river. Is this true?

No. Bathing Water Designation is for the benefit of current “bathers”.  Theres no requirement to improve facilities, or to carry out any other changes.

Cllr Katie Thornburrow has confirmed that the designation does not require new facilities to be built and the council has no plans to do so

I’ve heard people calling it a Designated Bathing Area or DBA, saying that this means it’s obvious its intended to attract people to a small designated area. Is this correct?

No. The correct name, used by Government is “Designated Bathing Water.” This is because bathing is NOT restricted to a small area. In a river, water flows though the site, so a large stretch of river benefits from clean-up as a result of designation .

Are you independent?

Cam Valley Forum is a voluntary group, established in 2001, registered with HMRC as charitable. We are entirely independent, and politically neutral. 

As our website states, “We work with our extensive network of partners to protect and improve the environment of the River Cam and its tributaries”  We frequently criticise the water companies and others for pollution and over-abstraction.

In 2021, when our volunteers started monitoring the Cam for faecal bacteria (ie bacteria from poo), we received a small grant of £1,500 from Anglian Water as a contribution towards the costs of laboratory analysis. In September 2022, Anglian Water took over the test program, and they are providing us with test results until September 2023.  We are publishing these on our website here

We think the public deserve to have more reliable, independent information on water quality, than that provided by volunteer citizen scientists like us, or by the Water Company itself. This is why we welcome the help of a very experienced and professional body like the Environment Agency, who have responsibility for monitoring Designated Bathing Water sites.

Will it be 100% safe? 

Bathing Water Designation will reduce the chance of diarrhoea and vomiting from ingesting faecal bacteria. 

Most people who swim in the Cam do so without problems, however wild swimming is never 100% safe, so you should make your own judgement (and keep your mouth shut while swimming).  For certainty about safety, we advise swimming in swimming pools like Kelsey Kerridge, Abbey and Jesus Green Lido where the water is filtered and chlorinated, and the pool is supervised by lifeguards.

If the site becomes a Designated Bathing Water site, the City Council will have to display the Environment Agency’s annual water quality rating, in order to help inform the public of the level of risk. In addition to this, we are also encouraging the Council to display some Wild Swimming safety advice, as Oxford City Council has done at their Designated Bathing Site.

AGM and Annual lecture: Monday 18 March 2024 7pm-9:30

David Attenborough Building (Seminar Room), New Museums Site, Downing Street. CB2 3QZ

  • AGM 7pm
  • Refreshments at 7.30pm
  • Annual Lecture 8.00pm

Annual Lecture: Can the Cam Flourish Again?

Can we transform our water infrastructure and farming so we become part of a healthy aquatic ecosystem?

Professor Simon Spooner.

As AtkinsRéalis Fellow Simon is developing nature-based catchment solutions to flooding, water quality, water resources, biodiversity and carbon sequestration.

“Through the centuries we have been reaching ever further upstream for fresh water and dumping our waste as close to our doorstep as we can get away with.”

In his illustrated talk, Simon will present some innovative approaches to living sustainably with our rivers, focusing on enhancing the water cycle and fostering healthy aquatic ecosystems that are integrated with the land they flow from. This transformation demands a shift in urban planning and agricultural practices, emphasizing small-scale changes and investments by individuals and communities, alongside the necessary large-scale infrastructure projects by governments and corporations.

He will discuss the need for new business models, supportive policies, technologies, and collaborative contractual frameworks to facilitate these changes at the local level, inviting discussion on how we might implement such ideas effectively