Author: Anne Miller

AGM and Annual lecture: Monday 24 March 2025 7:00-9:30pm

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

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

Annual Lecture: Earth, water, air and fire: how fixing and restoring our rivers is about so much more than water.

In this lecture, Craig Bennett,Chief Executive of The Wildlife Trusts, will explore how a focus on rivers can provide the foundation for sorting out many environmental challenges not normally directly associated with rivers, or water quality. What might this mean across the UK, but particularly in Cambridgeshire?”

Craig Bennet, Chief Executive, The Wildlife Trusts

Among many other accomplishments, Craig is Chief Executive of The Wildlife Trusts, Honorary Professor of Sustainability and Innovation at Alliance Manchester Business School, and an Associate Fellow of Homerton College (Cambridge). He is also a Commissioner on the UK Government’s Clean Power 2030 Advisory Commission. He has been described as “one of the country’s top environmental campaigners”, by The Guardian as “the very model of a modern ecogeneral” and was recently included in The Sunday Times Green Power List of the UK’s top 20 environmentalists.

Craig was formerly CEO of Friends of the Earth where he led the organisation to numerous campaign victories including on bees, fracking and against airport expansion.

Sewage Sleuthing the River Cam

Why is the Bathing Water quality so poor, and what should be done about it?

We held a well attended event in Newnham, Cambridge on 23 October 2024 to share the results of our investigations into the poor water quality in the River Cam, at the end of the first Bathing Season after achieving Bathing Water Designation.

Sewage sleuthing presentationDownload the slides here

Following the Environment Agency’s monitoring , it is clear that the official Bathing Water classification will be “poor”. This will trigger advice against swimming, investigations into the causes, and measures to fix them.

We’d expected a poor classification, but the results are shocking: every single E. coli test result is above the 90 percentile threshold of 900 colonies/100ml. The River Cam may well have the worst quality Bathing Water in the UK

Environment Agency Monitoring results for the River Cam, 2024 Bathing Water Season.

We want correspondingly urgent action to improve it, to protect the health of the many people that swim, kayak, paddleboard, punt and row on the Cam.

Our analysis of detailed monitoring done for us by Anglian Water during 2022-3 shows that Haslingfield Sewage works, 4km upstream is a big part of the problem. In summer, E. coli levels peak at the Sewage works, then steadily decline as the river flows past Grantchester Meadows to Sheep’s Green. In winter, and after rain, levels of E.coli are much higher, and they remain high as the water flows downstream

E.coli levels peak at Haslingfield Sewage Works, then steadily improve downstream towards Sheep’s Green

But our investigations show that other causes may also be contributing: its not JUST the sewage works.

These include frequent overflows from the sewage pumping stations in Harston, Haslingfield and Grantchester. These releases flow into various ditches, and then into the Cam

Dilute sewage in the street at Button End, Harston

The Rising Main (the pressurised pipeline taking raw sewage from the surrounding villages to Haslingfield Sewage Works) burst 3 times in 2022 and once in 2024

Raw sewage flowing from a burst Rising Main between Haslingfield and the Sewage Works in 2020

These various overflows have released sewage 35 times since January 2021.

This is in addition to the all too frequent overflows from the sewage works itself, which last year was revealed by Anglian Water’s EDM report to have been overflowing 30% of the time.

Surface water from Newnham Croft flows into the ditch at Paradise Nature Reserve. We think this may be also be contributing when it rains…

Newnham Croft surface water outfall into the ditch at Paradise Nature Reserve

After rain, the ditch goes brown. We’ve tested this for E. coli and as our presentation shows, after rain, E.coli levels reach 100,000 colonies/100ml . This shockingly high level is as bad as in the effluent being discharged from Haslingfield Sewage works.

We don’t yet know where this is coming from. Misconnections in Newnham could easily be a cause, because these are quite common, particularly from extensions when builders take “shortcuts”. These misconnections could be releasing sewage, or other “foul” water into Paradise Nature Reserve and the River Cam.

Dog mess might also be contributing.

A likely misconnection in Newnham Croft, with foul water pipes going into a rain water gulley

To help

  • Check that builders haven’t misconnected your drains (contact us if you want help)
  • Call the Environment Agency, immediately on 0800 80 7060 if you see suspected pollution incidents (this “evidence” helps the Environment Agency’s enforcement)
  • Never, ever, put wet wipes down the toilet (these cause blockages)
  • And join us on the ‘March for Clean Water’ on 3 Nov (show your support for tighter regulation, better enforcement and an end to pollution for profit)

We’ve organised a coach from Cambridge to the ‘March for Clean Water’, or you can make your own way by train. Do join us

Reserve your place on the coach here:

Sewage sleuthing presentationDownload the slides here

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

20240521-Closure-statement-RPO-contactDownload

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 

Areaminmeanmax
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.
Water saving tips.Download