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:
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
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- savewatersavemoney.co.uk 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 savewatersavemoney.com. 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.
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
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
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.
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.
The reservoir of the invasive weed, Floating Pennywort in the ditch between Fen Ditton ditch and the Cam has been in our sights for about a year. It is particularly important because now that the upper river is clear of Floating Pennywort, Cambridge Conservators are undertaking a major pennywort clearance project in the main river downstream of Cambridge. This ditch is now the main upstream reservoir.
Dealing with it has been a joint effort, led by Mike Foley.
Part of the problem was that a fallen tree was blocking access from the river, but ownership was unclear. It was clearly going to take a while to resolve, so Cambridge City Council lent us a boom to help contain the pennywort in the ditch until we could sort out what to do….
It took many many months, but finally, thanks to persistant hard work by Mike, much pouring over maps and many discussions with the Parish Council, various potential land owners and their agents, Jesus College kindly agreed to “take responsibility” for dealing with the tree.
South Cambs District Council accelerated the permit for the treeworks as much as possible, but the nesting season had started before we got the OK to proceed. However, once Mike had done a Bird Survey to show that all was clear, Bidwells came in and removed the tree.The following day a team of 13 from Cambridge based technology company Sentec joined Mike to clear the pennywort.
They made good use of a set of nets and rakes given to us by the Environment Agency earlier this year.
The ditch is now basically clear of pennywort, although we will be continuing regular followup sessions from the bank and water to remove remaining strands as they emerge as the weather warms up.
If anyone who lives in the Fen Ditton area would like to help, do let us know.
Environment Agency map showing woodland potential. Dark blue means “very high potential”
The Environment Agency has published a very interesting (but rather clunky) online map of the potential for tree planting.
This shows that they rate much of the land in the Cam Valley as “very high potential” for woodland planting.
Planting lots more trees could be a very attractive way of improving water quality. A Forestry commission expert pointed out to us that even relatively small bands of trees (5-8m wide) can be very important in protecting rivers from contamination by the excess phosphates, nitrates and sprays that would otherwise wash into the river from intensively farmed agricultural land.
In areas with public access he recommends planting willows (not Crack Willow!) Black poplar, Alder, Downey Birch, and lower shrubs, for example Gelder Rose.
The Environment Agency map is available online here . It covers the whole country, and lets you zoom in to see the potential in each tiny little river tributary, which is great. Unfortunately its a bit clunky to use and only works if you’re using Microsoft’s Internet Explorer web browser.
The image of the map above shows of the overview for the Cam Catchment. I have added the names of the key towns to make it easier to understand.
The Environment Agency’s user guide for the map is here
The Environment Agency is consulting on the future of the statutory river coarse fishing close season in England, which currently runs from 15 March to 15 June.
This is your chance to give the Environment Agency your opinion or submit evidence to support the case to retain, change or remove this close season. They would like to hear from as many people as possible.
They want to better understand the risks and benefits associated with any change and the potential impacts on fish stocks, angling and other wildlife.
The consultation is open now and the closing date for responses is 11 March.
On a lovely autumn morning, 8 of us cleared the Floating Pennywort from Swan Island cut. A plank on a ladder made a useful bridge.
After a couple of hours work, it was satisfyingly clear of pennywort.
We organised this working party at short notice, because we discovered this hidden reservoir last weekend… If not dealt with, it would soon break up in the frosts and spread fragments to re- infest the rest of the river.