Blog & News

Publication of our report “Let it Flow!”

River Granta at Stapleford, Sept 2019

Cam valley Forum publishes Let it Flow! – detailed proposals to restore the River Cam

Our new report – Let it Flow! – explains the environmental impact of water abstraction on the Cam Valley and calls for actions in seven main areas to protect and restore the river:

  1. Substantial reductions in groundwater abstraction from the aquifer that feeds our Chalk streams. Where the water environment is being damaged, licences need to be amended or terminated to deliver real cuts in actual abstraction, not just paper savings in licensed amounts
  2. Investment in new sources of public supplies. Proposed strategic north-south transfers of water should be extended to benefit the Cam Valley too. Locally, high river flows should be captured in a new reservoir in the lower Cam Valley, once they have flowed through it in as natural a way as possible, and be redistributed as necessary.
  3. Investment in water reuse and aquifer recharge schemes. Sewage treatment works need to be upgraded to deliver better treated water to be reused for public supplies and to recharge the aquifer and/or to support irrigation.
  4. Investment in the harvesting of rainwater and recycling of greywater. Our local planning authorities need to ensure that schemes to harvest and recycle water become commonplace and help to make Cambridge a ‘Water Sensitive City’.
  5. A step-change in attitudes to water use through metering, leakage control and demand management. Cambridge should become the ‘No. 1’ water-saving city and the Anglian Region the ‘No. 1’ water saving region in England.
  6. Significant reductions in water pollution and investment in work to enhance habitats and natural processes. Action is also needed to: reduce pollution from land, businesses and homes; and to rectify the impacts of past river modifications, which have reduced connectivity between reaches (e.g. weirs) and between rivers and their floodplains.
  7. Improved resilience, not only for public water supplies but also for the environment. An increasing population, economic growth, intensive land management, and climate change, will all bring new pressures to bear on the Cam Valley’s limited and precious water resources. We all have a moral obligation to protect our river environments for future generations to enjoy.

Our 12 further recommendations are being submitted to Water Resources East, the body currently charged with planning the future for water resources in our Region. We want to work with the other members of Water Resources East to create an ‘Integrated Water Resource Management Plan’ to secure the best possible outcomes from this process.

We commend Let it Flow! to everyone with an interest in the environment of the Cam Valley.  We would welcome comments and support and look forward to developing our ideas further in close consultation with all relevant interests in the months to come.

You can download the full Let it Flow! report here and the four-page summary with the 12 recommendations here

CVF Coronavirus Notice

During the coming months, in view of the considerable threat posed by the risk of viral transmission through close person to person contact please note the following:-

We shall not be organising group field visits, conservation work-parties or face-face committee meetings until further notice

We will continue our monitoring and campaigning activities and so welcome being alerted to River Cam related issues and to any of your observations of INNS (Invasive, Non-Native Species) such as Floating Pennywort or Himalayan Balsam. e-mail: We will continue to maintain a log of observations of INNS on our website, and identify hotspots where individual action would be useful.

We shall of course continue our occasional newsletter Cam Valley Matters, edited by David Brooks. Please do send us your River news. e-mail:

We encourage all our members and supporters to remain engaged with the natural environment to the extent that it is permitted.

However, irrespective of the dangers of COVID-19, rivers and watercourses are dangerous, particularly if you are on your own. If you wish to carry out conservation work, we strongly advise you to carry out your own risk assessment before starting work. For the avoidance of doubt, note that you will not be covered by CVF insurance during these self-organised outings.

19 March 2020

This policy will be revised at intervals, in accordance with government and scientific advice. Our latest version can be downloaded here

Himalayan Balsam survey report published

Himalayan Balsam at Audley End overspill loop

Download full report here

In 2019 Cam Valley Forum volunteers (led by Mike F)  carried out a catchment wide survey of the incidence of the invasive weed Himalayan Balsam.  The primary aim of this survey was to identify the key upstream hotspots on which eradication effort should be focussed.

These upstream hotspots are

  • Sparrow Hill (TL521364) north of Newport
  • Madgate Slade and in adjacent overspill ditches at Saffron Walden (TL531383).
  • SSSI site ‘Alder Carr’ at Hildersham, (with a few plants above this)
  • Coton Nature Reserve at TL414582.
  • Bourn Book (active eradication programme underway by WLBCN, CCV CRT and CVF)

Cam Valley Forum will be focussing on the areas adjacent to Cambridge, particularly Bourn Brook and downstream into Cambridge City but we hope our partners; the  Environment Agency, local Wildlife Trusts and conservation groups, will find this report useful in tackling the other upstream hotspots.

Himalayan Balsam is a problem because it is an extremely invasive non-native annual plant. It grows well in moist and semi-shaded damp places, predominantly on the soft banksides of slow-moving watercourses. Where it becomes dominant it can cause environmental problems:

  •  reduces biodiversity
  • can choke waterways leading to flooding
  • competes with native flowers for pollinating insects–especially bees
  • when killed by frosts, it leaves ground bare and vulnerable to erosion leading to bank loss and unwanted sediment in the water

Resources to help with eradication available here

How to Save Water, and the Cam

During the 2019 summer, the dry weather reduced our River Cam to little more than an elongated pond with a pathetic tickle over the weirs at Jesus Green. Some of the Cam tributaries dried up, many only flowing because they have been augmented by water from sewerage works

Over-abstraction of ground water has contributed to the drying-up of many of the springs that have fed our River Cam Chalk streams for millennia. Cambridge Water take 97% of their water from the chalk; Anglian Water abstract about 50% of their water from chalk aquifers to supply customers from Lincolnshire to the Thames. The rest comes from reservoirs. An ecological disaster is looming.  However, everyone has the opportunity and responsibility to try to lessen this crisis.

Things we can all do to help

The average water usage in England is 142 litres per person per day.  If water supply in low-rainfall high-growth Cambridgeshire is to be sustainable, this needs to be reduced to around 85 litres.  The Cam Valley Forum urges everyone to make a concerted effort to reduce the amount of water that they use, and here are 10 top tips.

  • Don’t flush every time you pee- ‘If it’s yellow let it mellow, if it’s brown flush it down!’
  • Reduce quantity of water in WC cisterns, or if they are dual flush, use the lesser flush whenever appropriate. You can get bags to place in cisterns, they are more effective than a brick, and Cambridge water are giving them away, together with other water saving devices, go to- and select Home tab.
  • Fit aerators to taps. These add tiny soft bubbles that reduces the flow of water by about half while maintaining the water pressure, they can be fitted to most taps and cost between £2.50 and £6.99 per tap from The water feels nicer and soaks better.
  • Have brief showers instead of baths. Install water saving shower heads, Cambridge Water are giving away shower heads that limit flow to 8L/minute, but better still are Ecocamel  shower heads  which aerate the water for a better soaking shower, while using about half as much water.  They can be bought online for £27.99p.
  • Don’t run the tap when brushing teeth. Keep a jug of water in the fridge rather than running water until it is cool.
  • Use a bowl when washing-up and only use the dishwasher and washing machine when they are full.When buying dishwashers and washing machines select ones that are water efficient. For example, energy star-rated dishwashers use about two thirds of the water that average dishwashers do.
  • Install water butts with drain downpipe connectors and water plants with rainwater or use waste water from the house.
  • Wash the car with a bucket and sponge rather than a hose.
  • 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.
  • Take prompt action to have any leaky appliances in the house, such as dripping taps or overflowing cisterns, repaired or replaced. Report any leaking water mains to the Cambridge Water Company on 0800 316 7676.

River Cam Manifesto

Bourn Brook July 2018

We have today published our River Cam Manifesto to urge everyone to wake up to the fact that all is not well with our rivers.

As the map below from the Environment Agency’s report for July 2019 shows, the flow rate in the River Cam flow is now exceptionally low, at just 33% of the long term average.

In part this exceptionally low river level is due to low rainfall (agravated by climate change), but it is also due to over abstraction of our precious ground water, which is reaching critically low levels.

We see this because our chalk streams, which are a globally important habitat, are drying up. Even when the stream is not totally dry, the water quality is often “poor” because there is insufficient water flow to dilute the pollution from sewage works, sceptic tanks and agriculture.

Few realise that in an attempt to save them, our chalk streams are being artifically augmented. About 20% of the groundwater that is pumped from our aquifiers is pumped to the head of the chalk streams and allowed to flow down them and ultimately out to sea.   This may disguise the problem, but it is no fix, and ignoring it will ultimately be a disaster for us all when the taps run dry.

The only solution is for us all to take action both personally and politically to save water and save our streams. And to start now. This includes:

  • Visiting and caring for our threatened streams
  • All of us using less water
  • Demanding that the new Local Plan requires all new housing developments to use “grey water” (eg for flushing toilets)
  • Requiring water companies to dramatically reduce leakage and invest in new reservoirs, natural water catchment and flood prevention
  • Giving our regulators teeth and the abilty to use them

For more detail read our  River Cam Manifesto

We also recommend the report Chalk Streams in Crisis from the Rivers Trust

Cambridge’s ground water level exceptionally low

The blue dashed line shows the lowest recorded level at this site

The Environment Agency’s July situation report for the East Anglia shows that Cambridge’s ground water level is already exceptionally low: the lowest ever recorded, and that it’s getting lower.   It was only the unusually wet winter of 17/18 that has saved our water situation from being even worse.

Cambridge and Breckland have the lowest groundwater levels in East Anglia

All the Environment Agency’s monthly water situation reports can be seen here

The Environment Agency has asked us to point out that, as stated in their reports, “All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained herein.”

Cambridge Water’s drought plan and advice on how you can help can be seen here

Balsam Bashing working party

Mike’s team of Cambridge Balsam Bashers set to work on clearing the invasive weed Himalayan Balsam from a long stretch of the nettle infested lower reaches of Bourn Brook and the Mill Race (just above Granchester)

The aim is to stop infestation around Cambridge, and ultimately (ie in future years) to work back up Bourn Brook and meet up with the eradication efforts been coordinated by the Wildlife Trust and others upstream on Bourn BrookIt was noticeable that there were very few plants on the South bank, thanks to vigilance by the anglers  over the last few years.

Part of the lower end of Bourn Brook were also only lightly infested, because they had been cleared earlier by canoe. Canoe work can be very effective earlier in the year, before the waterweed gets too thick.


Lower Cam pennywort working party. 29 June 2019

On the hottest day of the year so far, Cam Valley Forum and Cambridge Canoe Club held a joint working party to help Cam Conservators clear the invasive weed floating pennywort from the lower Cam, between Baits Bite Lock and Clayhithe.  (This is a continuation of our pennywort eradication project, which seems to have successfully eradicated it from the Cam above Cambridge)

We had 15 people: 3 working from the bank and 12 from canoes.

We were working together with Tom from Cam Conservators who was using their new “Conver” weed lifter boat.  The combination is very effective: the Conver deals with the bulk, but we’re very effective in picking up the little bits the Conver misses or drops.

There’s still more to do, especially between Horningsea and Clayhithe, but we’ve made a good dent in it.  Hopefully ultimately, (with the help of boat owners too) we’ll be able to eradicate pennywort as far down as Clayhithe

We finished with a very pleasant picnic in the shade on John Harrison’s meadow in Horningsea.