In some ways eco-warrior Paul Powlesland has the sort of zeal we need much more of. He cares enough about an overlooked London river to spend his own money trying to improve it. So, when the Environment Agency wrote to him warning that it was investigating works he’d done on the Alders Brook without a permit, it looked once again like a bureaucracy that had lost its purpose, persecuting someone trying to do the right thing.
I met Paul briefly a couple of years ago after he had given a talk on the Rights of Rivers, for which he is a passionate advocate. Curious about the arguments in favour, I had nevertheless been unconvinced. I couldn’t see what the granting of rights would do to improve a river’s health over and above the application of existing (or improved) environmental laws.
This kerfuffle with the Agency hasn’t done much to sway my scepticism. In fact, it begs the same question I had wanted to ask Paul as he rushed to the train station: “Once a river has rights, who will best speak for it?” A river’s interests aren’t always that obvious and the path to hell is paved with good intentions.
The story of Powlesland’s run-in with Agency has been very widely reported: splashed across The Guardian and The Daily Telegraph, featured in Channel 4 news, retold as far afield as The Times of India and all over social media. The stories all suggest that Powlesland was being threatened with prosecution for removing rubbish from a river, which on the face of it is absurd.
That didn’t quite ring true for me. The good folk of the River Wandle Trust have been taking rubbish out of that south London river for decades, without ever falling foul of the Environment Agency. They have done this work with the cooperation of the local council, who have provided lorries to take away the vast quantities of stuff that other no-so-good folk of south London insist on throwing in there: mattresses, tyres, shopping trolleys. You name it.
Volunteers on the River Wandle have been litter-picking for years without ever falling foul of the Environment Agency.
I couldn’t imagine why on the Earth the Agency would want to harry Powlesland for litter picking, and I suspected that they didn’t. I suspected, in fact, that they had taken exception to something else. The words “silt and weed” in The Guardian headline made me suspicious. The mention in The Daily Telegraph of the use of an excavator hired by Powlesland for £750 made me more suspicious. You don’t need an excavator to pick litter. So, had he actually dredged the river of “silt and weed” in the name of cleaning it up?
Sure enough, when the Agency finally relented and informed Powlesland that they wouldn’t be taking further action the letter alluded to “flood risk activity” consisting of “dredging, raising or taking of any sand, silt, ballast, clay, gravel off the bed or banks of the Alder’s Brook”. Somewhere on the Roding Trust Facebook feed there is a film of a digger slubbing mud out of the channel. Harmless enough, perhaps, but ordinary mortals do need consent for that kind of work, so to just crack on without it and post the evidence …
Clearly, Powlesland is very much motivated to do the right thing. Clearly, he is frustrated by what he sees as petty-fogging bureaucracy standing in his way.
But so was John Price, a farmer who was jailed for 12 months for taking an excavator into the River Lugg and dredging the bed of that highly protected river. John Price’s crime was far, far worse than Powlesland’s intervention, but the point is … John Price thought he was doing the right thing too. He thought he was protecting the village from flooding. And the media, en masse, portrayed him as a Robin Hood hero. He wasn’t. He badly damaged salmon spawning grounds, and if anything, his tidying up of the River Lugg will have made the flooding worse.
Powlesland’s work on the Alders Brook won’t have done either of those things, but if he dredged silt out of it he may have temporarily stirred up pollutants and caused oxygen depletion downstream. Besides, dredging silt out of the Alders Brook is also a Canute-like exercise.
The Alders Brook is not a tributary of the River Roding, as described in the newspaper reports. It is the natural course of the upper reaches of the tidal River Roding. Further down the valley the same relic natural course was once called The Back Water and is now almost entirely erased. The first edition Ordnance Survey marks the head of the Alders Brook where it leaves the diverted course of the modern River Roding, with the words “Ford. Ordinary Tides flow to this point”.
The Alders Brook is part of the estuarial River Roding, naturally tidal upstream as far as the ford.
The diversion of the modern river course flowed from there to a paper mill in the village of Great Ilford. No doubt the paper mill is long since obsolete but the modified course and its impact on river morphology remains. The Alders Brook is not a free-flowing stream, rather a part relic of a tidal estuary. Once it would have drained under gravity twice a day, and this would have kept its main channel free of accumulating sediment. But estuaries are, by their nature, muddy places where any interruption to gradient will gather silt and mud. The upper parts the Alders Brook have natural gradient, but the lowermost reach takes a sharp, unnatural turn to the east, and if anything, the river is trying to climb uphill as it rejoins the much diverted and much modified main Roding. It is, therefore, a sump and will always fill with silt.
A LiDAR image of the Alders Brook – the thin, meandering line in the centre. Its ability to transport sediment is now severely compromised by a railway line and diversion at the downstream end. The railway and the infrastructure around it form what is, essentially, a dam across the valley floor.
Throughout eastern England, we’ve done stuff like this: we have boxed in estuarial reaches of rivers and reclaimed the land either side of them. Now, they can be miles from the sea with all vestiges of that transient landscape buried under trading estates, retail parks and railway lines, and the expectation is that these meandering courses should behave like rivers. They can’t.
Removing accumulated silt may look like restoration, but unless the free-flowing tidal processes that once maintained the channel are also fully restored—which, in urban east London, is impossible —the exercise becomes one of perpetual maintenance.
None of this is to question Powlesland’s motives, which are clearly driven by a passion to improve his local river. But that doesn’t mean every enthusiastic intervention should simply be waved on through without the troubling business of conforming to the consenting process.
And it does beg a question about river rights. In the few places these have been enacted they’re just too vague to be meaningful: “the right to flow” “the right to be free from pollution”. For all our failures to actually impose environmental laws, these laws protect rivers in terms that are generally much clearer.
Rights would require somebody to speak on behalf of the rights-holder and who is best going to do that when one person’s idea of an improvement may be another person’s idea of environmental damage? A river that looks untidy may actually be a haven for wildlife. A fallen tree might look like obstruction, when it’s actually habitat. Silt looks dirty when it might be the stucture of the channel. Weeds look like neglect when they are vital to the flow, temperature, oxygen and nurient levels.
Passionate river guardians standing up for vague rights and emboldened to act unilaterally without consent because they feel that right is on their side: that could just as well become an army of John Prices, as an army of Paul Powleslands. We should be careful what we wish for.
The Roding Trust volunteers go out in all weathers and do hard work to make their corner of the planet better. We need their passion, for sure. The Environment Agency were a bit heavy-hoofed in this case, and that didn’t sit well in the context of their reluctance to prosecute much more obvious and damaging environmental offences. Powlesland has described dozens of illegal discharges of raw sewage upstream on the same river: Theydon Bois works, for example, spilled 85 times in 2025. Not all of those can have been in “exceptional weather”.
But right now, if I want to restore a river I have to draw up a plan, back it with evidence and apply for permission. The application procedure is frustratingly slow and sometimes the edicts from the folk granting or denying permission feel baffling, or obstructive. I wish the process could be better and argue that it should be. But on the other hand, if we want the Environment Agency to protect rivers, then we shouldn’t object too hard when it does.
Coda.
So, if the Roding Trust can’t meaningfully restore the estuarial Alders Brook because there’s just too much of London in the way, what could they do to revive it and create a lovely waterscape? I seriously doubt the brook serves any flood relief function nowadays: so, bearing in mind it can’t become free-flowing again and will always be a silt trap, I’d cut off the inflow and outflow and turn it into a meandering still-water. This way, silt would take much, much longer to accrete and could be carefully removed once a decade by suction. It would be clear-watered and full of life and pretty enough— one hopes— to shame even the worst of litterbugs.
The project would require consent, however.
A once tidal creek that is now a meandering, freshwater pool: an example of the best possible outcome for the modern Alder’s Brook?
The Environment Agency (EA) has finally replied to the River Tarrant Protection Society (RTPS). The reply doesn’t reflect well on the EA.
The RTPS is a local group, campaigning for the protection of the River Tarrant, a Dorset chalk stream that historically supported 5 Domesday watermills and even now remains a spawning stream for Atlantic salmon, but which nowadays dries all too frequently because of abstraction. The RTPS has shown that before the 1950s the steam rarely, if ever, dried in its lower reaches. After the onset of groundwater abstraction the lower stream began to dry in extreme droughts – eg 1976, 1989 – catalysing the formation of the protection society.
The situation had been bad for decades. Now it is much worse. In 2018 Wessex Water completed work on an area ring-main, designed to relieve abstraction pressure on chalk streams in the neighbouring and highly protected Avon catchment. As a result, abstraction around the River Tarrant increased, since when the stream has dried in its lower reaches every single year.
The one year in the past ten when the stream did not dry was 2017, when the local pumps were turned off, and that was in spite of the fact that 2017 was drought year for chalk streams.
The RTPS has compiled a report consisting of historical evidence, ecological evidence, local testimony and modelling that collectively – in the opinion of the RTPS – suggests that abstraction is the cause of this increased drying.
RTPS has asked for a meeting with the EA to discuss their concerns, and for the potential abstraction impacts to be investigated more fully in the next round of AMP investigations. These are hardly unreasonable requests, especially in light of the fact that Atlantic salmon from chalk streams have very recently been shown to be a genetically unique and critically endangered sub-species. In the Stour catchment the salmon are on the very edge of survival.
My past few blogs have detailed the argument and the local EA’s inflexible and partisan approach to the matter. The area office commissioned a comparative and isolated review of the approaches to groundwater modelling taken by the Wessex Water / EA teams and John Lawson, the independent hydrologist working for RTPS. The review concluded that John Lawson’s approach was too simplistic, whilst also admitting that the Wessex model did not actually perform very well in its modelling of the impacts of the Black Lane abstraction.
The local EA didn’t consider any of the other evidence. As you can see below, the EA now considers the matter closed.
“Dear RTPS,
Thank you for your response* which I read with interest. I note the concerns you express but I find myself somewhat at odds with your assessment.
[*This being the RTPS response to the EA’s review of John Lawson’s modelling]
I feel it would be irresponsible for the Environment Agency to move away from a chalk basin groundwater model which is founded on accepted hydrogeological principles. Although the model created by John Lawson is of interest, I don’t feel it’s clearly based on conventional hydrogeological interpretation. I would also note that I do not feel that criticism of the independent reviewer as being justified, as she is highly qualified and respected in her field.
Although I personally felt the review of the two modelling approaches to be the fundamental issue that needed reviewing first, I should also point out that the status of the watercourse is constantly under ecological review, to assess any change in status under the Water Framework Directive. The element that leads to the water body not achieving overall good status is fish status. In this regard, it is annually reviewed by my fisheries colleagues and a lot of work has subsequently been carried out to address many of the concerns they identified over barriers, as well as some additional habitat restoration.
You have put forward a number of proposals relating to the operation of water company assets in the lower Stour. I think it’s important to clarify that the EA largely leaves the day-to-day operation of water supply sources to the water company to deliver, while our role is then to ensure they remain compliant within their licence conditions. How the water company choose to operate their sources varies throughout the year and from year-to-year dependent on many factors, which are laid down in their Water Resource Management Plans. These documents are reviewed and updated on a five yearly cycle, with work commencing again next year. You may contact the water company with your suggestions, but I suspect your proposal, though appearing simple on paper would have significant cost, infrastructure and resilience implications, especially in drier years. This could leave them exposed with the risk of not being able to supply their customers without breaching their licence conditions.
I think it should be mentioned, that when Wessex Water held the final meeting at the end of the five year AIM trial, the fundamental issue that they identified may have been overlooked or misinterpreted. The gauged data shows over time that the lower 3 kilometres of the river are become leakier. About ten years ago, at times when the river channel becomes perched, usually late summer to autumn, the losses amounted to around 1M/L per kilometre. So a 4ML/d flow entering this section would mean the lower river remained connected to the Stour. By the end of the period these losses had doubled or even tripled. Now once the groundwater level has fallen below the bed of the river, abstraction becomes irrelevant in this respect and it’s all about bed leakiness. The groundwater level can continue to fall beyond this point, but it won’t impact the river. It appears as if the riverbed has become leakier over time, possible due to vegetation clearance or other activities. Whether some form of natural lining trial might be an option such as chalk puddling I don’t know, but it could be considered. I have mentioned this to our chalk stream coordinator to review its feasibility. Please note no funds are currently available for such work but this may change in the future.
I feel now from a water resources perspective that we have exhausted all our options, following trials, investigations and extensive monitoring. Should some new data be brought to my attention I will give it due consideration, but the Environment Agency has a remit to protect all the watercourses within our area, and we need to concentrate our limited resources where they’ll achieve the best outcomes.
Kind regards … “
I should leave readers to form their own conclusions given the EA’s approach somewhat speaks for itself.
But I can’t help but point out:
The RTPS didn’t ask the EA to “walk away from their groundwater model”, rather RTPS suggested that the model may not be entirely correct. Who really thinks that groundwater models are infallibly accurate?
The RTPS didn’t criticise the independent reviewer, but rather her review and more especially the limited terms of her enquiry which were set by the EA.
These are classic straw man tropes and I am surprised by them given the loss of respect and credibility that will inevitably follow.
As to the alternative explanation that the riverbed “has become more leaky”* perhaps I really should let that speak for itself!
Of course the Tarrant has become more leaky. That’s the point. The question is WHY?
*This may be one for a more detailed rebuttal in another post. The idea that the separation of water table from river bed leads to an absolutely binary transition, is nonsense. Apart from anything else, it is perfectly obvious from the flow data that the water table peels away from the river bed, and that the drying extends by varying distances upstream depending on the water balance.
A fascinating comment was recently added to my post The Slow Death of a Chalk Stream. Nick Walton – a hydrogeologist with 50 years experience – wrote:
“Hydrological/hydraulic models can only ever approximate reality, and depend upon a wealth of assumptions and averaged, default and chosen input parameters, together with a few hard, but time-limited data points (mostly fairly ‘recent’ borehole, spring and river data). Whilst this can get close enough to reality for practical / operational purposes in more homogeneous hydraulic media, in the case of the infinitely variable and unknowably complex 4-dimensional hydraulic pathways within the Chalk aquifer, the reliability of the model outputs depend upon their achieving an approximation to observed reality at just a few observation points, leaving the vast majority of the aquifer, in all four dimensions, untested and potentially quite different from expected modelled results.”
Given the above, said Nick, historical evidence, empirical data, local knowledge and some hydrological common sense are worth a lot and shouldn’t be dismissed.
Those four things are exactly what the River Tarrant Protection Society report contains. The RTPS is saying that when all the evidence is taken in the round the case is strong enough to justify further, detailed and truly independent investigation.
This shouldn’t be a debate about whether the Wessex Basin Model is more sophisticated than the CSF modelling. It clearly is.
The issue is whether the confidence placed in the Wessex reports conclusions is justified, given the limitations of the underlying data, the acknowledged uncertainties in conceptual understanding, and the internal inconsistencies in model performance across the Pimperne and Tarrant catchments and beyond to the edge of the Stour.
Data from an impacted system
All models are limited by the quality of the data that is fed into them — and here the data are limited and impacted. The Wessex model is built on:
groundwater level records (largely post-1970),
short-term stream flow gauging with spot meters (primarily 2015–2017)
short-term targeted pumping and switch-off tests,
a system that has been subject to decades of abstraction.
In other words, the model is based on data extracted from a system that is already altered from its natural state.
Without continuous flow records prior to the 1970s, and without direct measurements of groundwater–surface water interactions before large-scale abstraction, surely historical and qualitative evidence becomes more, not less, important? And yet it is largely excluded from the formal assessment.
Of course, Jane Dottridge wasn’t commissioned to comment on this other evidence. She nevertheless described it as “anecdotal”. I don’t think that’s fair. Anecdotal refers to an account or short narrative that is subjective, unreliable, or hearsay. Mapped Domesday mills are not anecdotal evidence.
Pimperne calibration
As to the models: Jane critiqued the one-dimensional simplicity of the CSF conceptual model. However, in spite of its attempts to capture the more complex reality, there is still uncertainty and assumption in the Wessex model, especially around the Pimperne–Tarrant interfluve.
Jane does highlight this: “the Pimperne calibration is not very good, with a very smooth modelled recession in contrast to the marked break in slope of the observations. Some of the gauges on the middle Tarrant (Rushton, Preston Farm) also show the same feature”
But she makes little of it. In the next paragraph Jane writes: “The conclusions appear to be justified based on the evidence presented in the report”
I don’t follow that logic. To recap, the conclusions of the report are:
Tarrant: only the abstraction pump in the valley (Stubhampton) is relevant to flows in the Tarrant. The stream is negligibly impacted by this abstraction “along the perennial reach” * and the ecology is not adversely impacted.
Pimperne: the abstraction at Black Lane does not impact flows in the Pimperne.
That is a very clear no impact statement given:
The calibration is poor in the Pimperne and the lower Tarrant.
The Black Lane abstraction is a high % of the catchment recharge.
The groundwater boundary is modelled as fixed with no impact on the neighbouring Tarrant.
Surely the mismatch between the strength of no impact conclusions and the poor calibration warrants a furrowed brow.
* This is a variation on a rhetorical ploy I’ve seen before: if a stream is dry then abstraction is ipso facto not impacting the stream. It’s also evidence of my point about how the impacted state can become the new baseline. The RTPS contends that the lower river is naturally perennial.
Known knowns, known unknowns and unknown unknowns.
The Wessex report presents a conceptual model strategically refined by fieldwork that included stream-bed surveys, weekly observations and spot-flow measurements, new boreholes to investigate the interfluve, switch-off and pumping tests.
Accordingly, the model was refined to simulate lower transmissivity beneath interfluves, higher transmissivity in valley bottoms and the introduction of “unmapped faults” in the chalk – horizontal flow barriers – to improve calibration.
Surely these iterative refinements highlight, rather than resolve, the uncertainty? The interfluve behaviour was not predicted by earlier model versions, new borehole data required significant reinterpretation of the system and the fault-line is partly imposed through model structure, inferred – because the river dries – rather than directly observed in the geology.
The cornerstone conclusion ref the Tarrant — that abstractions outside the catchment have no impact — depends on the assumption of limited cross-interfluve connectivity. And yet groundwater catchments are known to shift with hydraulic gradients and Jane’s review confirms that groundwater boundaries can and often do vary over time and with rising and falling groundwater levels. If they do this, they can also vary because of abstraction pressure.
A central element of the Wessex argument is that switch-off and pumping tests define what they call “zones of influence” of abstractions and that impacts are therefore spatially limited.
This interpretation is not supported by general hydrogeological principles. Why does it pass, unchallenged?
Short-duration tests reveal immediate, local drawdown responses but do not capture longer-term system adjustment. They don’t capture the delayed propagation of pressure changes, the redistribution of groundwater flow paths, or slowly accreting capture from inter-connected water bodies.
The absence of observed drawdown at a location during a short test simply cannot be taken as evidence of no long-term hydrological impact.
Pick’n’mix
There is also evidence of expedient selectivity in the Wessex report and even Jane points this out. Where the Wessex model performs reasonably well – the Tarrant – it is used to support conclusions. Where it performs poorly – the Pimperne – then alternative methods are used: pump tests and empirical observations.
This pick’n’mix kind of undermines confidence in the whole thing surely? The analytical method is not consistent across the whole piece.
John’s CSF model may be pilloried for its simplicity, but at least it treats the whole study area in the same way. The Wessex Water approach ought to weaken the Environment Agency’s confidence in the system-wide conclusions, particularly those relating to this cross-catchment impacts we insist are plausible but which Wessex Water hotly denies.
What about 2017?
I’ve already underlined the coincidence between a long-term shut down 2016 to 2017 of the Black Lane pump in the neighbouring Pimperne valley and the fact that the summer of 2017 was the one year in the past ten that the lower Tarrant did not dry. This is such good evidence that the Black Lane pump may well be having an impact on the Tarrant, or the Black Lane and Shapwick pumps in tandem, especially when one remembers that the spring of 2017 was bad for chalk streams. That was the year that I took photographs of drying streams all round London, the Ver, Chess, Misbourne, Beane, Rib, Ash and others.
The year the Chess looked like this, the River Tarrant kept flowing.
Wessex Water has an answer: they claim that late summer rain prevented the Tarrant from drying when it was otherwise on course to. I put this to John Lawson and he went away to look at the rainfall figures over a longer time-series, to see if this late summer rain was an anomaly that plausibly did make the difference.
As you can see, the summers of 2015, 2021 and 2023 were similarly wet or wetter than 2017, but the river still dried. Whereas the the preceding October 2016 to March 2017 was unusually dry and that’s what usually determines flows in the following summer.
In summary
There is a mismatch between limited range of data (no consistent, long-term flow gauging), incomplete understanding of the aquifer, poor calibration in the modelling and confidence in the conclusions.
The purpose of highlighting these issues is not to suggest that “we are right and Wessex Water and the Environment Agency are wrong”. Instead it is to demonstrate that:
alternative models produce plausible results which do suggest an abstraction impact,
key assumptions (e.g. fixed catchment boundaries, limited zones of influence) are not definitively proven,
the current evidence base does not support a strong “no impact” conclusion.
Given all the above surely it would be prudent to treat the current findings as provisional rather than definitive and look for a more robust truly independent investigation, with scope not limited to model comparison.
Let’s not forget, this stream is used for spawning by Atlantic salmon. The stream may not be as protected as the Bourne and Wylye, but the salmon is. These fish are genetically unique to chalk streams and the Stour’s population of these fish must be the most endangered stock of all.
Oh and just one more thing …
Underlining the mismatch between what we know and confidence in conclusions, it is worth addicting that recent research into the Chalk aquifer by Andy Farrant and others at the BGS has highlighted the greater-than-previously-recognised role of karstic dissolution features and preferential flow pathways in chalk. These can provide localised areas of enhanced permeability that are not necessarily captured in regional groundwater models. Hydraulic connectivity may well occur along pathways that are not predicted by averaged aquifer properties or detected by limited observation boreholes. This must be relevant where abstraction alters hydraulic gradients, potentially activating or enhancing flow along such pathways?
Sure, this does not demonstrate that such connections exist between the Pimperne and Tarrant catchments, it does underline the uncertainty associated with assuming that lower-transmissivity interfluves act as hard hydraulic boundaries.
As this photo of an exposed chalk face shows, chalk aquifers are pretty darn complex. But that doesn’t mean simple models can’t tell us useful things about their fundamental behaviour or that sophisticated models are, per se, more accurate.
In my last post I questioned why the Environment Agency confined its review of the River Tarrant Protection Society (RTPS) report to a comparison between two modelling approaches.
I argued that the Chalk Streams First (CSF) model—a simple, lumped parameter model—was never intended to replace the more complex 3-D model used by Wessex Water, but rather to highlight uncertainty. Several hydrogeologists, including the independent reviewer, have previously suggested that such approaches can be used in a complementary, tiered way, with monitoring data providing essential context.
In that light, it makes little sense to treat this as a modelling contest in which the limitations of one approach invalidate its findings. Model outputs should be interpreted alongside other lines of evidence.
The independent review compared:
the Wessex Water Middle Stour report (the official position), and
the RTPS report on low flows and drying
with a focus on hydrogeological data and modelling.
In this post I consider that comparison in the light of Jane Dottridge’s review (attached to my previous post), focusing specifically on the conceptual and methodological validity of the CSF model.
Assessment versus indicator
Jane was asked to comment on the validity of the RTPS findings on abstraction impacts, and to consider the Wessex report by comparison. She concluded that the CSF model does not “provide a more reliable assessment of abstraction impacts than the Wessex model”.
However, the RTPS report did not claim to provide a more reliable assessment, but rather a more reliable indicator. That distinction matters. An assessment implies a definitive evaluation; an indicator signals a relationship or pattern without claiming certainty.
The CSF model was presented as part of a broader evidential framework. Its outputs, taken together with other observations, were used to question the certainty of Wessex Water’s conclusions. Judging it as if it were intended to deliver a standalone assessment risks setting up a straw-man comparison.
The conceptual model
Jane states that the CSF model is highly simplified and suggests first of all that it has no conceptual basis, then later that it lacks a sound conceptual basis. There is some ambiguity here: whether no conceptual model exists, or whether the one used is considered inadequate.
In practice, the CSF model is based on a clearly defined—if simple—conceptual model. It assumes:
a fixed groundwater catchment based on topography
uniform transmissivity
a broadly synchronous rise and fall in groundwater levels
a distributed pattern of spring discharge across the valley
These are simplifications of a complex system. In reality, groundwater catchments shift, transmissivity varies, and flow processes are spatially heterogeneous. But the question is not whether the model captures every detail—it does not—but whether it is appropriate for its intended purpose.
There is ample precedent in groundwater science for simplified conceptual models, particularly where the aim is to identify dominant controls or test the plausibility of observed relationships.
Model complexity should be proportionate to the question being asked.
Empirical relationship between groundwater and flow
The CSF approach is grounded in an empirical observation: that groundwater level and streamflow are closely correlated in chalk streams.
John Lawson has shown – using historical data – that, within relatively tight bounds, when groundwater levels are at a given elevation, streamflows fall within a given range. This close relationship appears to hold across long time series and across multiple different chalk stream catchments. John has looked in detail at the Rivers Kennet, Og, Misbourne, Chess, Ver, Mimram, Beane, Ivel and Darent, with some examples shown below.
Note. 1. baseflows derived from gauged flows using baseflow separation software. 2. Plotted baseflows usually lead GWLs by 2-3 weeks
And, of the course the River Tarrant.
The implication is that groundwater level is the dominant control on flow, with abstraction largely affecting flows indirectly by lowering groundwater levels relative to their natural state.
This is not a theoretical construct imposed on the system, but a pattern observed in the data and then represented mathematically.
The CSF equation and non-linearity
The CSF model expresses this relationship in the form:
Q = a(GWL – b)^c
where the constants are calibrated to fit observed data, where the constants are calibrated to fit observed data. Q is flow and (GWL – b), is the height (h) of the groundwater at the observation point over the stream bed at the discharge point.
As shown on the above plots for the Rivers Chess, Misbourne, Mimram and Ver. The relationships between GWLs and baseflows is very strong for “pure” chalk streams with baseflow indices over 90%, like the Chess and Misbourne in the above plots. In rivers like the Darent, with mixed geology including some tertiary deposits, the baseflow indices are below 80% and the relationships show more scatter, but are still plain to see.
A key feature of the relationship is that it is non-linear: increases in groundwater level produce disproportionately larger increases in flow. The model captures this behaviour through the exponent (c), which typically lies between 2 and 2.5 as seen on the plus above.
This non-linearity can be understood heuristically. As groundwater levels rise:
the area of saturated ground contributing to spring flow increases, and
the hydraulic response of the system becomes more pronounced
Together these effects produce a more-than-linear increase in discharge. While the precise physical mechanisms are debated — ranging from valley geometry to fracture density—the existence of non-linear behaviour is widely observed in the data.
The CSF model does not claim to resolve all underlying processes, but it does provide a consistent way of representing this empirical relationship.
Calibration and transparency
Jane raises concerns about how model parameters — such as subsurface flow and specific yield— are derived.
In the CSF model, these parameters are obtained through calibration: the constants are adjusted until the model reproduces the observed relationship between groundwater levels and streamflows over historic records.
This is a standard empirical approach. The parameters effectively encapsulate the combined influence of aquifer properties such as permeability, transmissivity and storage (a) and valley shape combined with other components of the non-linearity, such as fracture density rising with altitude (b).
The method is described in the RTPS report (page 22), including the treatment of throughflow and specific yield. While simple, it is transparent: the model is designed to reproduce observed system behaviour rather than simulate all underlying processes explicitly.
The key question is therefore not how the parameters are derived in isolation, but whether the calibrated model reproduces reality with sufficient fidelity. On that measure, the fits to historic data are strong.
Is simplicity a weakness?
Prior to the Affinity Water conference in 2022, the CSF model was reviewed by several hydrogeologists. While they noted its simplicity and raised questions about parameter estimation, they did not dismiss the approach. On the contrary, they regarded the results as promising and worthy of further consideration.
Andy Binley wrote: “I must say that the modelling results and analysis of historic data appear convincing to me. You have modelled a substantial set of historic records using a simple lumped approach – the fits to data are impressive and appear to outperform the EA model.”
Jonathan Paul wrote “The reports showcase an interesting, if highly simplified, analytical relationship between groundwater level and river discharge. Initial results look very promising, but greater clarity in how your exponents a and b were obtained would be welcome.”
Jane herself noted in earlier correspondence that the model was “a neat little model” and more satisfactory than some alternatives, albeit highly simplified.
This highlights a tension in the review. The same simplicity that was previously seen as acceptable — within a defined scope — is later treated as a fundamental weakness.
Yet simplified models have a recognised role. They are often used in early-stage assessment, to identify key controls and sense-check more complex analyses. If they can reproduce observed behaviour reliably, they can provide a valuable benchmark against which more elaborate models can be tested.
Conclusion
The CSF model is not a replacement for detailed 3-D modelling, nor does it claim to be. It is a simplified, empirically calibrated tool designed to capture the dominant relationship between groundwater levels and streamflow.
Its conceptual basis is explicit, if simplified. Its parameters are derived transparently through calibration. And its outputs align closely with observed data across multiple catchments.
In that context, the key issue is not whether the model is simple, but whether it is useful. If it consistently reproduces observed behaviour, then it has a legitimate role — particularly in testing the robustness of conclusions drawn from more complex models.
To dismiss it on the basis of its simplicity alone risks overlooking precisely the kind of evidence that can help identify uncertainty in groundwater impact assessments.
With uncanny timing (following my post Tuesday last week), on Friday the Environment Agency forwarded to the River Tarrant Protection Society the adjudicatory report of their independent expert. (I’ve posted a copy at the foot of the page but have redacted a few personal details)
I received a lot of interested feedback from last week’s post. My intention had partly been to help inform other groups facing similar struggles in other parts of the Chalk, so I was very pleased that I seemed to have done that and to have catalysed a conversation about the uneven, David versus Goliath contests we face.
I’m uneasy about the EA’s approach to this case. Why take so long to respond? Why be so apparently reluctant to engage with the proactive, positive suggestions in the River Tarrant Protection Society (RTPS) report? Why not agree to a meeting? Why set out with an adjudicatory contest between models – which is almost bound to find in favour of the status quo – instead of addressing the full package of evidence?
A quick bit of background.
Please read my previous post for the fuller picture, but in short:
The River Tarrant is a chalk stream in Dorset where locals have long been concerned (50+ years) about the impact of abstraction.
It is a breeding stream for critically endangered Atlantic salmon.
The lower stream is drying far more frequently now than it did in the past. We don’t know for certain the flow patterns before the era of abstraction but there are no records of lower river drying before the 1950s (by contrast, there are records of natural upper river drying, for example in 1929) and there are five Domesday mill sites on the middle and lower river, which suggests the stream was reliably perennial.
As abstraction has increased from the 1970s to today the drying frequency has climbed from about once per decade (1976, 1989, 1995) to every year (2015, 2016, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025).
In 2018 Wessex Water was obligated to lower public water abstraction in the Bourne and Wylye catchments. To achieve this they constructed a grid to move water north from “under-utilised sources” in the Stour valley.
As part of this process the Environment Agency asked Wessex Water to produce an environmental impacts report into any possible impacts on the chalk streams of the Middle Stour, specifically the River Tarrant, the Pimperne Brook and the North Winterbourne.
The review concluded that:
only a single, small and long-running pump impacted flows in the Tarrant and by only a negligible amount.
a single, much larger pump had no impact on flows in the Pimperne winterbourne (nor the neighbouring Tarrant)
impacts on the North Winterbourne were negligible.
The grid went ahead, since when the Tarrant has dried every year.
In 2024 the River Tarrant Protection Society sent an independent report authored by John Lawson to the Environment Agency which questioned the Wessex Water assertion that the abstractions were having no impact on either the Tarrant or Pimperne. The report used the results of relatively simple “lumped parameter” modelling to show that there may indeed be an impact, and added a considerable weight of historical and recent empirical evidence to back up its claims
In the face of this uncertainty the RTPS has asked for more detailed investigations and has also proposed a scheme of abstraction realignment that would alleviate the drying in the Tarrant.
The Environment Agency has taken a long time to respond and thus far the terms of reference for their investigation have been very limited.
Independent review
Jane Dottridge, an expert hydrogeologist with Mott McDonald, was asked to compare the two modelling approaches: Wessex Water’s modelling (developed with the EA) compared with John Lawson’s modelling. To quote Christopher Greenwell, the EA Water Resources Lead, “I wanted to focus on the two modelling approaches first, since this formed one of the most fundamental challenges within the RTPS report … What Jane has done is not simply to consider John Lawson’s alternative approach but also to reassess the approach undertaken by Wessex Water during their investigation of the impacts of the Middle Stour sources.”
The RTPS was not consulted on the scope, terms of reference or the choice of reviewer.
Jane Dottridge previously reviewed the Wessex Water Middle Stour report in 2018. She has stated in her letter / report that she draws on her prior work as external reviewer to the Wessex Basin Model and her knowledge of that model.
More than that, Jane has encountered John’s work before, in another context. In preparation for a meeting convened by Affinity Water about the River Ivel in 2022, Jane was recommended to me as someone who might take an independent, helpfully critical view of John’s work and modelling approach. She sent some very useful notes of quite a technical nature. Arguably, her in-a-nutshell verdict was summed up in her statement: “My problem with this model is that it is very 1-d and doesn’t report any water balances. But it is a neat little model and much more satisfactory than some of the others I’ve seen recently.”
This we thought fair enough. John’s modelling wasn’t intended to rival, let alone replace the more complex 3-D modelling used by water companies and the Environment Agency. Instead it is proposed as a solid sense check, especially when the claims of water companies seem questionable, a tool for grass-roots organisations that can be used to usefully question unjustified certainties around these oft repeated claims of “no impact”.
In the meeting itself Jane was more critical of John’s modelling than she had been in our correspondence, describing it as a circular argument with a fitted-up recession to make calibration look right and “pop out some numbers”. It took Rob Soley to propose that the lumped parameter model had its value as a “first pass” to identify potential issues. Another hydrogeologist who we had spoken with before the meeting – Andy Binley – also defended John’s model for what it is, a simple, numerical model calibrated to predict flows, not all the other complexities of an aquifer system. Jane suggested the idea of a tiered approach to modelling – begin with simpler lumped parameter models, progressing to more complex physics-based models if simpler models don’t provide enough certainty.
Finally she added – and I have related this discussion not only because the roles of different complexities of modelling were not judged as mutually exclusive by Jane, Rob or Andy, but also because of Jane’s final point: she said that “models should be backed up by data and monitoring“.
So, why limit the scope of the review?
Christopher Greenwell stated that he wanted to focus on a review of the modelling approaches since “this formed one of the most fundamental challenges in the RTPS report”. RTPS weren’t given an opportunity to influence this decision, or to argue that John’s modelling outputs were part of a rounded package of evidence that included historic testimony, news reports and empirical observations.
We can see in Jane’s letter that the scope of the review did indeed focus solely on hydrogeology and groundwater modelling and that it excluded ecological, historical and qualitative evidence. This has the effect of narrowing the debate to something more like “which model is better” instead of addressing the more appropriate question: “what does the the sum of the various strands of evidence say about possible or probable abstraction impacts?”
Clearly, hydrogeology is an inexact science, is inherently uncertain. Groundwater systems — especially chalk — are structurally very complex and models of them are really only crude approximations of the living entity, no matter how much refinement is built in. They are dependent on assumptions and do not constitute primary evidence. Good scientific practice, therefore, should integrate the modelling with the other evidence. Which is exactly what the RTPS report did.
The EA’s approach – at least thus far – is a sort of backwards hydrogeology. It excludes archaeology, geomorphology, ecology, historical records, empirical evidence, testimony and conflates modelled output with evidence in the real world.
Besides, the RTPS model was never intended to win a modelling contest. It was intended to demonstrate that an alternative conceptual model can reproduce the observed behaviour of the stream and suggest that therefore the Wessex Water conclusions may be unsafe.
WFD rules
It is also worth pointing out that WFD assessment rules specifically state that decisions should be made on the weight of evidence, not a single line of analysis. If there is credible uncertainty, plausible mechanisms of impact and observational evidence consistent with impact – all very clearly set out in the RTPS report – then a regulator cannot safely conclude “no impact”.
The legitimate role of historical and qualitative evidence
The RTPS report uses various strands of evidence to try and establish:
the baseline condition of the stream
changes in the flow regime over time
the timing of the changes relative to the advent and then increases in abstraction.
For example:
The lower river dried rarely, if at all, before 1950 when abstraction began.
Between 1970 and 2000 the lower river dried about once per decade.
In the last decade, when abstraction has increased yet further, it has dried almost every year.
The exception of 2017 coincided with a long-term shutdown of Black Lane pumping station
This is very solid evidential reasoning, layering historical, hydrological, circumstantial and mechanistic evidence. The RTPS report advances a very legitimate scientific hypothesis, of which the modelling is just one part.
Thus far the Environment Agency’s approach:
Places too much reliance on model supremacy. The review as framed thus far implies that a model provides a more reliable basis for conclusions than any other strand of evidence. Models are inherently uncertain.
Fails to apply “weight of evidence”. The EA review evaluates the models but does not integrate them with the unarguable flow-regime changes, the ecological evidence, the historical evidence, the observed anomalies (2017).
Narrows the focus to short-term datasets. Historical evidence, for example Domesday mills and the presence of Atlantic salmon, provide a legitimate long-term context and capture a picture of the system behaviour before any monitoring record. This is really valuable information and should not be ignored. If you exclude these you bias analysis to short-term datasets that are all influenced by abstraction.
Misunderstands the RTPS objective. The RTPS model is criticised for its simplification of aquifer properties and structure and lack of conceptual detail. However, the RTPS model was not intended to outscore the Wessex Basin mode, rather to challenge and question its unjustified certainties.
Excludes the RTPS from dialogue. The RTPS sent their report 7-months ago and requested a meeting. Thus far the only meaningful engagement has been the receipt of this report.
By turning this into a modelling contest the EA – thus far – appears to have stacked the deck in favour of the status quo. The EA’s approach is at odds with the more inclusive way forward agreed in during the framing of the multi-lateral CaBA chalk streams restoration strategy. Recommendation 11 in the strategy advocated the importance of knowledge and model sharing and said it was important to “include stakeholders in the discussion and decision-making”.
**
In my next post I will take a look at the Wessex Basin Report, the RTPS report and Jane Dottridge’s adjudication and try to show why – even under the terms of the comparison – the RTPS case is strong and should not be dismissed.
The little River Tarrant is a beautiful chalk stream in Dorset, the site of five Domesday watermills and the home of spawning Atlantic salmon. The lower river has dried occasionally in the past but never before the era of groundwater abstraction. Now it dries every summer. Locals say this is down to increasing abstraction. Wessex Water says otherwise.
The March issue of The Field includes a feature by me on the poor little River Tarrant in Dorset. I first wrote about the unnatural drying of this stream 30 years ago after it vanished through its riverbed in August 1995, leaving 100s of trout dead in the caked mud.
The slide I took in 1995, the morning I went back to the Tarrant and found the river had vanished overnight
Back then, although abstraction had started to increase, the total loss of the lower river was relatively rare. Now, it dries in its lower reaches every single year. That and the fact that, in spite of this annual, unnatural drying, the river is assessed by the Environment Agency as “supports good ecological status” for flow brings into the spotlight the state of play in our work to mitigate and reverse abstraction’s impacts on chalk stream health.
The River Tarrant is a metaphor for the stasis in the regulatory system. The way this lovely chalk stream has been exploited and ignored over the decades is shameful.
To condense its story before I get into the techie stuff: the River Tarrant is a small chalk stream in Dorset, a tributary of the Stour. It is a slope-face stream, meaning it rises within the outcrop of the chalk downs which run north from Blandford towards Shaftesbury and flows south and east down the strike of the chalk slope. This makes it a classic, natural winterbourne in its upper reaches. The river length rises and falls as the groundwater in the unconfined, outcropping chalk aquifer rises and falls. It can dry, also naturally, in its lower reaches too, where there is a fault line in the chalk running perpendicular to the valley. As groundwater levels fall through the summer and especially in droughts, the lower river loses water to the ground.
However, the extent – by that I mean the physical and temporal extent – to which the Tarrant is a natural winterbourne is the subject of some debate. Historical evidence strongly suggests that the Tarrant is only a natural winterbourne in its upper reaches downslope as far as Tarrant Launceston, where old maps and LiDAR indicate that a meandering channel, suggestive of perennial flow conditions, begins.
Tarrant Launceston, where the valley opens out and there is evidence in the planform and floodplain of a perennial channel
Research by Dr David Solomon for a report recently commissioned by the River Tarrant Protection Society (more on that very comprehensive report, primarily authored by John Lawson, later in this post and a link at the end) has shown that the River Tarrant did occasionally dry further down the valley in the past, before groundwater abstraction was much developed, but so rarely as to make the local press when it did so.
It dried in Tarrant Monkton – a little further downstream than Launceston – in 1929 and 1933, both years of severe drought. There is no historical evidence of it regularly drying up in the lower reaches, however, albeit in 1970 Dr Stanton, a hydrologist, wrote: “In exceptionally dry years the river is dry just above the confluence with the Stour”. We know it dried in 1976 and it clearly shrank away to almost nothing in 1989 as noted by the National Rivers Authority, by which time the river was being more heavily abstracted.
The River Tarrant once supported several water-mills, at least five of which were Domesday mills. While the Domesday book did record “winter mills” molinum hiemale, none on the Tarrant are so described. All of the Tarrant mill sites are downstream of Tarrant Monkton, lending more weight to the idea that our ancestors preferred to construct mills where flows were reliable.
The mill site at Tarrant Crawford Abbey seems particularly anomalous to the modern-day ephemeral flow regime of the lower river. This was a substantial mill with a dedicated water-retaining structure and leat, sited very close to the confluence of the main Stour and another watermill – Keystone Mill – that would have been a better option and wholly reliable if the Tarrant had tended to dry.
Why build a pre-Domesday mill at St Mary and All Saints Abbey on the Tarrant if the flows there were ephemeral and a perennial mill existed only a few hundred yards away at Keyntson Mill on the main River Stour?
Meanwhile, Atlantic salmon persist in behaving as if the Tarrant is not a natural winterbourne. They are mentioned in 19th-century issues of The Field as regularly coming up the river to spawn, and there are numerous records of salmon in the river in recent years, including of salmon parr in the now all-too-frequent and necessary fish rescues. As is well known, salmon tend to spawn where they were themselves spawned: they imprint on the chemical signature of the water and stones in which they hatch. That genetic memory and behavioural fidelity – which goes back tens of thousands of years – ought to tell us something: salmon don’t spawn in natural winterbournes. Any salmon that chose natural winterbournes in the past will not long have succeeded in passing genes and progeny to the next generation.
A salmon parr from the Stour close to the Tarrant tributary
All of this and more – for example, the memory of ancient locals interviewed by my wife Vicky in 1995 – strongly suggest that the Tarrant is naturally a perennial chalk stream downstream of Tarrant Monkton, and that while it might naturally have diminished in its lower reaches in drought years, it didn’t tend to dry up. There is no documented record of the lower river drying before groundwater abstraction began.
So, how come it now dries in the lower reaches almost every year?
In 1995, when we rescued all those fish and failed to rescue so many more, the drying came as a shock: I had known the stream since 1987. It had dried in 1976— a drought comparable to 1929— but kept flowing for 99.9% of the next 19 years, with only the lowermost kilometre briefly drying in 1989. I fished it often in the early 1990s when two- to three-pound trout were not unusual. It was my best-kept secret. And yet, in eight of the past nine years, the lower river has been dry for between 46 and 120 days in the year.
The Tarrant, especially the lower Tarrant, has changed. Why?
The dried out lower Tarrant in 1995. It had dried before, in 1976, and 1989, all years of severe drought under an already heavy abstraction regime. Since 2017, it has dried every single summer.
“Just one more thing …”
The answer, I believe, lies in the telling fact that the one year— 2017— in the past decade when it didn’t dry in the lower reaches was the one year when Wessex Water shut down its Black Lane pumping station, which lies in the next valley over by the Pimperne Brook.
If Columbo were a natural history detective, he would at this point stop and say, “Just one more thing …” then ask how much it had rained in the preceding winter. Not much, is the answer. The spring of 2017 was a disaster for chalk streams: I was commissioned that year to take photos for WWF of all the chalk streams near London that were bone dry, also largely because of over-abstraction.
And yet, this one year of all years, the lower Tarrant kept flowing?
Wessex Water claims that the Black Lane pumping station cannot impact flows in the Tarrant, not least because there is a hill in the way.
And yet, water companies are often the first to point out that subterranean catchment boundaries are not the same as surface watershed boundaries and are dynamic too, capable of naturally migrating as groundwater levels rise and fall. For example, the aquifer under the true Winterbourne in that area, the ephemeral stream that confluences with the Stour on the opposite side of the valley from the Tarrant, and tellingly called “Winterbourne,” is also connected to the Bere Stream in the neighbouring Piddle catchment. In numerous meetings, this natural phenomenon of dynamic groundwater boundaries has been spelled out to me, as water company hydrogeologists caution against the simplistic notion that reducing abstraction in a given valley will lead to restored flows in that valley.
As this image from the University of Wisconsin neatly shows, groundwater divides can very much be shifted by abstraction pressure
And yet, conversely, the same water companies have also argued for the existence of glass walls between one chalk valley and the next. The Lea, for example, is very heavily abstracted, but apparently, that impact simply can’t translate across to the neighbouring Ver or Mimram. The abstraction in the Beane simply can’t affect the Ivel, or vice versa, etc. Like those watershed boundaries, the argument is dynamic and tends to suit the point being made.
As John Lawson’s report shows, there are several abstraction pumps in and around the Tarrant, and groundwater abstraction has crept up slowly over the years. The one source within the physical, surface catchment – Stubhamptom – is relatively small and has been running since the late 1950s. But there are much bigger pumps at the aforementioned Black Lane (just over the catchment boundary), and Shapwick (close to the confluence with the Stour), and Sturminster Marshall (a little further down the Stour valley), as well as Corfe Mullen, which is slightly further afield.
The aggregated impact of just the former three climbed from about 5 ml/d in the early 1970s (by when Stanton observed that the lower river dried in exceptional droughts) to about 10 Ml/d in the early 1980s, and peaked at about 15 Ml/d in the 1990s, when I was forced to rescue those trout in the 1995 drought.
By the early 2000s, the aggregated abstraction of these three pumps had fallen back to between 5 and 10 Ml/d. Then in 2016 and 2017, abstraction was reduced to about 6 Ml/d and in 2017 for a short period, to almost zero. By the end of 2017, it had ramped back up steeply to about 15 Ml/d, as the Wessex Water grid came online and “underutilised” sources in the Stour valley were used to aid reductions in the more protected Avon catchment.
Since then, the Tarrant has dried every year.
Wessex Water maintains that their sophisticated tests and modelling show that the Black Lane and Shapwick pumps don’t affect flows in the Tarrant.
Their case rests on the analysis of what are called switch-off tests, when they shut down pumps and look for the rebounding impact on groundwater levels in the surrounding area. This helps to define the ‘zone of influence’ (a misnomer – see my argument below) or more accurately the ‘cone of depression’, a funnel-shaped depression in the water table: a bit like the vortex that descends to a plug hole.
The cones of depression of either Shapwick or Black Lane do not reach the Tarrant Valley. At least not enough to influence drying, Wessex Water says, adding that an impact is exceptionally unlikely because the chalk between the valleys is less ‘transmissive’ (i.e. the movement of water through the chalk is more restricted) than within the valleys.
Their findings have been accepted by the Environment Agency.
A map of the River Tarrant showing where the river is a natural winterbourne, where it loses water in the lower reaches, the location of pumping stations, and their so-called “zones of influence”
Bringing sticks to a gunfight.
As a community of campaigners, we have struggled to fight the over-abstraction of our chalk streams in no small part because we don’t easily understand the way groundwater drives river flows or the ways groundwater abstraction impacts river flows. As a perfect example, the idea of lessening abstraction in summer – which more or less every lay person still thinks is the right time to reduce abstraction (or the worst time to increase it) – made it all the way from being a collective NGO recommendation to becoming an Ofwat incentive, when it is generally the least effective time to limit groundwater abstraction, because the impact of the reduction is not generally felt at the time it is made.
We are easily baffled, firstly by the sometimes counter-intuitive ways in which groundwater and flows respond to abstraction and secondly by the sophisticated arguments of the water companies or their consultants. If we were universally better informed, we might do a better job of combating the radar chaff thrown in front of our heat-seeking ire.
I knew nothing about all this groundwater stuff this time in 1995. I just had a strong hunch that abstraction must be to blame because it is logical to conclude that if you take water out of a natural river system, it must impact flows from that system. That logic still holds, by the way. But there are complexities to this mephistophelean science, and it is best we try to understand them.
Ob-fudge-scation
Three decades ago, water companies, the river authorities, and their consultants generally tried to fudge the impact of abstraction on river flows. In systems as complex as spring-fed rivers, it was easy and too tempting to dissemble and deflect.
As just one example, in the 1990s, Atkins wrote a report on abstraction impacts in the River Kennet. They stated:
“There is no clear evidence that groundwater levels over the catchment have been affected by groundwater abstraction.”
“There is no strong evidence for any change in the distribution of minimum groundwater levels over the catchment…”
“Ongoing abstraction does not have a cumulative effect… Both groundwater levels and surface flows stabilise at a lower level…”
That last statement is particularly disingenuous, deliberately designed to confuse the lay reader. It allows for the stabilisation of groundwater at a lower level, having previously stated that there was no evidence this was occurring and then conflates the idea of ecological damage only with cumulative groundwater mining.
Notice the phrasing, the refrain of “no strong evidence” as a caveat? We could characterise this as systemic minimisation and an insistence on evidential uncertainty. It is designed to disable the protest. People had noticed the drying up of chalk streams, but countering this kind of specious guff was very challenging unless you had a PhD in hydrogeology and didn’t work for a water company, the agencies or one of their consultants. Which is no one with a PhD in hydrogeology.
In fact, the NGO movement has been turning up at gunfights armed with sticks for several decades. Only John Lawson – who started out battling that exact same Atkins report and the unsustainable abstraction of the River Kennet where he lives – has made a really effective stand here on behalf of the NGOs. He deserves a sainthood, let alone a knighthood. One of the cleverest people I know and a very good, highly qualified engineer, he and his work are routinely dismissed and patronised by the hydrogeological cabal.
Computer says “we don’t know”
While the socio-economic benefits are still just as real today as in the 1990s, water companies no longer fudge the theoretical case quite so brazenly. In practice, however, and on a case-by-case basis, they argue the toss every single time. They have very strong economic motivations to do so. And they manage quite successfully too, because as our knowledge of these systems has become more sophisticated, the ability to hide action behind uncertainty has increased.
Our understanding of the chalk aquifer has developed over recent decades, so that what was once seen as three basic strata is now understood as many different strata comprising different chalks of varying age, hardness and structure, intersected by layers of less transmissive horizons, riven through with karstic flow-ways. About this infinitely complex underworld, the more we know, the less we know for sure.
Groundwater modelling has also become much more high-tech over recent years. We now have conceptualised, computerised aquifers, with gazillions of cells imitating the aquifer properties, which can run numerous scenarios and impacts. And yet – so it seems – we can never know enough to state anything for certain. Thus we have replaced the fudging with an insistence on preceding any action with full knowledge, attained only via immensely sophisticated modelling that is privy to water companies and the Environment Agency, the two players who are motivated to maintain the status quo.
There’s too much money at stake for water companies. Too much work at stake for consultants. The socio-economic value of groundwater renders the precautionary principle a pipe dream. eNGOs and protesters are still impotent and hobbled by their relative lack of expertise and resources.
And thus every chalk stream in which the abstraction pumps run is a new arena for endless investigation.
So, it is with the Tarrant. The complexity allows the can to be kicked. Again and again and again.
Newsflash!
The River Tarrant Protection Society commissioned John Lawson to write his report well over a year ago. It contains a very cogent case for casting doubt on the joint Wessex Water and Environment Agency conclusion that the river Tarrant is unaffected by local groundwater abstraction. It includes a pragmatic proposal for how to relieve pressure on the River Tarrant and asks, at the very least, for the Tarrant to be properly included in the next round of AMP investigations.
There is a great deal of historical and anecdotal evidence in the report, but the bulk of the report covers John’s analysis of the formal modelling and his own, simpler, but empirically accurate modelling methodology (which hydrogeologists tend to dismiss). This shows that the recent actual flows only fit the modelled outputs when the pressure on the regional groundwater table, including that exerted by the pumps at Shapwick and Black Lane, is taken into account.
John’s conceptual model – I will try to unpack it below – underpinning his numerical model is based on the idea of the aquifer as a regional entity, that allows for the inclusion of neighbouring catchments. In theory, this inclusion could radiate as far as the boundaries of the aquifer. In practice, John does limit it to keep the data input manageable. John’s conceptual aquifer is – I will argue – theoretically accurate, but hotly denied by any water company that encounters John’s work.
John shared his report with Wessex Water and with the Environment Agency last September. Christopher Greenwell, the EA’s water resources strategic lead, replied a few weeks later, promising a detailed review of the report and a meeting to discuss, with an update by the 12th December 2025.
The update never came and had to be chased. The EA replied in mid-January to say that the groundwater team was reviewing the report. In March this year, Christopher Greenwell replied, saying that his groundwater colleagues would commission a review (so had they been reviewing the reports in January or not?) and a comparison of John’s groundwater approach, as well as the methodology used in the Wessex Water / EA chalk basin model, “to be carried out by an external party to avoid bias and give greater confidence to all parties”. Asked for a bit of clarification, Christopher confirmed that the review would not concern itself with anything in the report other than a comparison of the conceptual models.
So, John’s David to the Wessex Water / Environment Agency Goliath then? With the review conducted by a third party who is fully objective? We shall see.
In the meantime, back to the complexity … and those conceptual models.
Groundwater for Dummies
It really isn’t that complex. Or rather, any complexity that exists overlies a basic, unarguable simplicity. Groundwater abstraction from a spring-fed system will lower stream flows from that system. There’s no real, honest debate over whether it does, or even by how much it does (over time, by the same amount as the abstraction). The debate, such as it exists, is over where the impact is felt and more challengingly, when it is felt.
This provides all the wriggle room needed, however.
Time
The role of time can be difficult to get your head around, but – at first – let’s imagine the underground aquifer as a large surface lake, with many streams and rills running into it from the surrounding hills, but only one river draining it. Loch Tay, for example. If we eliminate evaporation, and any loss of water through the lake bed, the amount of water flowing out of the lake must equal the amount coming in.
But the correlation between inflow and outflow is not continuously simultaneous. When it rains it will take time for the water in the lake to rise and force more flow to leave the lake. And when it stops raining and the lake level is high, it will take time for the lake level to fall and the outflow to diminish, until it once again balances the inflow.
The system is in a state of dynamic stability and equilibrium. Inflows, lake level and outflows all vary all the time, as rain comes and goes, but ultimately inflows equal outflows over time.
Once that is grasped, it only takes a bit of imagination to increase the size of this mind’s-eye lake and appreciate that time will lag to a greater and greater degree between the impact of inflow on lake level and outflow as the lake gets bigger. A headwater stream in flood rushing into Lake Windermere (6 square miles) will force up the level of the lake and the outflow more quickly than it would rushing into Loch Neagh (150 square miles).
If we now add another form of outflow (let’s say we drill a great big pipeline through the hill and divert a large proportion of the lake’s recharge into a neighbouring valley), the former outflow (the river draining the lake) will have to go down.
However – this is key – it will take time for the new outflow to drain the lake down to the point where it captures that former outflow.
But capture it, it will.
How long it takes depends on the relative size of the new outflow and the size of the lake. But, no matter the size of the new outflow, there must eventually be an impact on the former natural outflows that exactly equals the new outflows, and the mechanism for that impact is the lowering of the lake level. Even if the abstraction is small, maybe only 5% of the former discharge, and the new outflow is a long way away from the natural outflow, it will be felt, in time, once the lake has lowered by the commensurate amount.
That surface system is fairly easy to get your head around.
Going underground
The complexity comes when you turn the surface system into a groundwater system. The fundamental concept of the water balance remains exactly the same, however, meaning that you can’t add an extra form of discharge (abstraction) without lowering the former natural discharge.
Historically, water companies have argued that you can and have used obtuse arguments to say as much. Setting the precedent for this, in the mid-19th century, the London Water Company started to abstract water from the River Gade, a chalk stream still bedevilled by abstraction. When the millers on the Gade complained, the London Water Company recruited scientists to argue that their abstraction didn’t and couldn’t lower the river flows. They were taking water, so the Victorian boffins argued, from a limitless well so deep underground that it wasn’t connected to the surface system, something the millers were able to show was nonsense. The courts found in the millers’ favour but kicked any reparation into the long grass of the future, a debate and conclusion which is eerily familiar in the Chilterns to this day.
Knowing therefore that when the lake becomes an aquifer, the impact of the abstraction remains non-negotiable, the components of when and where do become harder to pin down.
When and where
We have already seen in the lake analogy that the timing of the arrival of impact at the outflow varies according to the size of the lake because the new outflow must reduce the water level in the lake in order to have an impact on the former outflow.
This is the same with an aquifer. A groundwater abstraction must first lower the water level in the aquifer in order to then capture former natural flow from the stream. Thus, in the first instance, an abstraction – depending on where it is sited – may have an almost undetectable influence on former stream flows while it takes water from the volume stored in the aquifer. Eventually, however, the abstraction will reduce the storage and lower the groundwater levels enough to establish a new dynamic balance in the level of the aquifer, after which ALL of the abstraction is captured from the former natural flow. This split over time between water taken from storage and then water taken from flow is illustrated in the diagram below.
The key idea is this:
The means by which groundwater abstraction captures stream flows is by a reduction in the storage of the aquifer and a lowering of groundwater levels to establish a new dynamic balance.
This lowering of the water table changes the hydraulic head across the entire aquifer, which is what lowers the natural flow.
This basic and inalienable truth was defined by Theis in 1940, but is befuddled all the time by water companies as they smudge the issue of whether any particular abstraction is having an impact on any particular stream.
Wessex Water, for example, argues that relatively short-duration switch-off tests (mentioned earlier) define the boundaries of the cones of depression in their analysis of abstraction impacts around the Tarrant and then misleadingly conflate these boundaries (partly by now renaming the ‘cones of depression’ as ‘zones of influence’) with the limit of the influence of the particular, individual abstractions.
They argue this, in spite of the fact that the impact of any given abstraction extends – in theory – infinitely from the location of the abstraction, its only real boundary being time. The cone of depression is simply the measurable drawdown around a pumping well, forming a gradient that drives water to the wellhead. The edge of the cone is not a physical boundary at all, it is a detection threshold where the drawdown is less than any possible measurement error.
This diagram tries to show that the radiating impact of an abstraction in a uniform, infinite aquifer is – in theory – bounded only by time.The cone of depression is only the limit of the measurable drawdown.
In short, the use of the cone of depression is a water resources construct to help simplify modelling and analysis. In reality, the system actually responds as a continuous, radiating field of change in hydraulic head.
How groundwater abstraction actually affects natural systems.
The so-called zone of influence is actually only the measurable depression, one that is imposed on a much more widespread reduction in the dynamic level of the water table, that reduction exactly equating, over time, to the reduction in head needed to capture former natural discharge and establish a new dynamic balance. Groundwater abstraction alters the natural distribution of hydraulic head everywhere in the system.
Although the system’s boundaries are – in theory – only limited by time, in practice they may effectively be defined by other factors (and Wessex water contends that these factors are relevant). These could include:
impermeable layers – for example thick layers of clays and flints between layers of chalk.
aquifer boundaries – the chalk aquifer obviously ends where the chalk ends. Although it may well connect with other aquifers, the boundary of the chalk may mark an effective boundary for the purpose of analysis.
recharge boundaries – large rivers or lakes / wetlands can supply the water being demanded by the abstraction and therefore limit the effective growth of the water-table reduction. It’s possible the River Stour floodplain is a recharge boundary in the case of the Tarrant.
changes in transmissivity – this is what Wessex Water rests much of its case on, especially the transmissivity under the catchment boundary.
Those effective, possible limits notwithstanding, groundwater abstraction is actually a time-dependent redistribution. As I have shown, it can take a long time for abstraction to capture former natural flows.
Stage 1. Duration – days, weeks or months.
The water demanded by the pump comes almost entirely from storage. The impacts are localised and at this point they are indeed mostly felt within the cone of depression.
Stage 2. Duration – months to years.
The abstraction begins to impact nearby streams and wetlands. This is when the abstraction starts to impact hydraulic gradients in an ever-widening orbit, taking less and less water from storage and increasingly more from changes in the boundary flows.
Stage 3. Duration – long-term new equilibrium, years to decades.
This is the stage beyond which the groundwater abstraction must, according to immutable laws of physics, take its water from the capture of former natural discharge. Most of this will be a reduction in the former groundwater discharge to the chalk streams. Some will also come from “induced recharge”, driving leakage from the stream bed (this is absolutely what is happening in the lower Tarrant), and from lowered evapotranspiration (because the water table is lowered).
Over time, the depletion from former natural discharge approaches the pumping rate, until almost all is taken from the stream system.
Just as it can take a long time for abstraction to lower groundwater levels and capture former natural outflows, it must therefore take a long time for a reduction in abstraction to lead to fully recovered groundwater levels and a full restoration of former natural flows.
Switch-off tests lasting only a few days, weeks, or even months will do nothing more than allow the cone of depression to refill and so help define its boundary. This is not the same thing as the limit of the boundary of impact.
The important point to underline in the case of the Tarrant is that groundwater divides are based on hydraulic head and that divide can move with abstraction pressure. Abstraction can also steepen the gradient of the hydraulic head on one side of the divide relative to the other, causing water to flow towards the pump, relative to the natural system
This means that theoretically, it doesn’t necessarily matter if the Black Lane abstraction is in the neighbouring valley, or that there is a hill in the way, or even that the chalk is marginally less transmissive under the hill. These pumps can very much impact flows in the Tarrant by altering the hydraulic boundaries a long distance from the pump in ways that might not easily be detectable except as diminished stream flow.
Short duration switch-off trials
The switch-off trials that were used to define the boundaries of the cones of depression around the Tarrant lasted only several weeks.
The Black Lane pump was shut down between 9th June and the 15th August 2016. Continuous pumping at a high rate then followed for the next month until September 15th. Both the recovery of groundwater levels and the ensuing drawdown and second recovery were analysed by Wessex Water and used to infer that the so-called zone of influence didn’t extend to the Tarrant. Adding to the weight of evidence was an analysis of groundwater gradient undertaken in 1985 which showed steep groundwater contours under the Pimperne – Tarrant interfluve, suggesting that the chalk here is of lower transmissivity.
The Shapwick pumps were shut off for only eight days in July 2017. They studied groundwater responses around Shapwick and up to and in the Tarrant valley. There was a visible rebound near the pump, but no discernible rebound on the Tarrant interfluve, or the Tarrant valley. Wessex concluded that the river gravels in the Stour valley supply most of the water to the Shapwick pump.
In both cases, a midsummer switch-off of nine weeks, let alone of only eight days, cannot reasonably be deemed long enough to allow regional groundwater levels to recover, when true recovery would need one or two years or longer.
It seems to me that Wessex Water and EA’s logical reasoning is flawed.
The degree to which other limitations – such as lower transmissivity under the interfluve, or a possible recharge boundary in the Stour gravels – have a controlling impact is debatable on a case-by-case basis, but one needs to get the evidence and reasonable conclusions in the correct order.
In other words, it is not sustainable to:
subject a natural system to abstraction
observe a subsequent change in flows in the River Tarrant
confidently attribute that change to some other as yet unknown cause (Wessex Water posits a more leaky river bed than in the past)
confidently state that the impact cannot be caused by abstraction because
the boundaries of a measurable zone of drawdown do not reach the Tarrant
and short-term switch-off tests do not show a recovery in borehole levels that are some distance from the pump
This is confirmation-bias reasoning.
What do we KNOW in theory?
We know for certain that abstraction must – eventually – cause a commensurate reduction in former natural discharge, mostly stream flows.
We know that it can take a long time (months to years) for abstraction to remove storage and lower water-table levels to the extent that it captures those stream flows.
We know – vice versa – that it can take a long time (months to years) for the cessation of abstraction to lead to a full recovery of water-table levels and former stream flows.
We know that there is no theoretical limit to the distance over which an abstraction’s impact may be felt.
We know that factors such as transmissivity may create an effective limit to that distance.
What do we KNOW in practice?
We know that aggregate groundwater abstraction in and around the valley has climbed steadily since the 1970s.
We know that before 2017 the lower River Tarrant dried in 1976, and in 1989/90 and 1995 (all severe droughts).
We know that since 2015 the lower River Tarrant has dried every summer except one (none of which were severe droughts).
We know that the recent drying outside droughts has coincided with the highest aggregate abstraction rates from the three pumps in and close to the valley, over 10Ml/d from Stubhampton, Black Lane and Shapwick, and over 20Ml/d when including Sturmister Marshall.
We know that the one year in the last decade when the lower Tarrant did not dry – 2017 – was both a very dry year AND the one year when the Black Lane pump was switched off for several months and the aggregate abstraction rate fell right back only a few Ml/d .
We know that there is no documentary evidence that the lower Tarrant regularly dried before the era of groundwater abstraction, although there is such evidence for drying in the upper river, which one would expect to dry naturally from time to time.
We know that there is evidence to suggest the lower river flows were reliable before the era of groundwater abstraction.
Occam’s Razor …
states that when faced with competing hypotheses, the one with the fewest assumptions is probably the best.
The River Tarrant Protection Society’s hypothesis is that the drying of the lower Tarrant is caused by the local groundwater abstraction, especially its increasing rate since 2017.
Wessex Water’s hypothesis is that abstraction cannot impact flows in the Tarrant because the chalk under Tarrant Pimperne interfluve appears to be less transmissive and because short-term shut-off tests show that the measurable cones of depression do not reach the Tarrant valley, even though we know that cones of depression do not mark the limit of potential influence. They posit that the drying of the lower Tarrant may be caused by an unexplained and un-evidenced increase in the leakiness of the riverbed and that the lack of drying in 2017 is explained by some heavy rainfall in the late summer.
I truly hope that the review commissioned by the Environment Agency proves to be genuinely independent.
Wessex Water* is not objective. Their regional water plans and the use of Stour sources to relieve abstraction pressure in the highly protected Avon SAC are upset by the idea that abstraction should also be reduced in and around the River Tarrant.
But the Tarrant is a chalk stream and a nursery stream for critically endangered Atlantic salmon. The Environment Agency would not be doing its job properly if it ignored clear evidence that abstraction was damaging salmon spawning and nursery habitat.
The River Tarrant Protection Association is asking that the abstraction impact on the River Tarrant be properly investigated, not dismissed, or filibustered and that their pragmatic proposal for a solution to the problem be considered.
*I feel it would only be fair to add neither am I! The Wessex Water team – though we disagree on this important issue – are decent and fair. WW has a statutory duty to supply water to customers and for every abstraction they give up, they must find water elsewhere. This is no easy task. But at the same time we have environmental laws in the WFD and elsewhere that define the limits of impact that statutory duty can cause. It’s up the regulators to adjudicate.
Above: the Hogmsill chalk stream in south London spilling sewage in a light shower in 2007
Repatriation of ownership, public listing, long-term funding, transparency & accountability, independent regulation. It’s not rocket science.
Below is a three-minute summary of how that might work — and why the solution may lie somewhere between privatisation and nationalisation. Read beyond that for the full article.
The Water Industry Debate: A Short Version
Public anger over Britain’s polluted rivers has surged and campaigners are calling for the water industry to be nationalised. After decades of sewage spills and dividends flowing to investors, bringing water back into state control feels like justice.
But nationalisation alone will not necessarily clean our rivers. In the UK, pollution in Scotland and Northern Ireland—where water is publicly owned—are comparable to England and Wales. Across Europe, excellent water systems exist under a variety of ownership models. What the good versions share are long-term investment, governance, and strong regulation.
Britain’s sewage crisis is too deeply embedded to be sorted with a change of clothes. We inherited Victorian sewers that mix rainwater and wastewater, meaning rain regularly overwhelms the system and forces discharges into rivers. Add chronic under-investment (by government and private industry) going back 50+ years, population growth, urban paving, and patterns of heavier rainfall, and the pressure has only increased.
The other part of the failure is financial and regulatory. Water infrastructure requires large capital investment upfront that must be repaid slowly through bills. This should produce a stable, low-risk utility attractive to long-term investors. Instead opaque ownership and weak regulation allowed debt to balloon while infrastructure investment stagnated. Shareholder capital injections have been minimal, with most spending effectively directly funded by customers through their bills. Regulators focused solely on keeping prices low while environmental oversight weakened.
Nationalisation risks recreating the same problems. Two of the institutions that failed most visibly—Ofwat and the Environment Agency—are already public bodies. State ownership does not automatically deliver stronger accountability or better environmental outcomes. The lesson from countries with world-class water systems, such as the Netherlands, is that success depends on transparent governance, specialist institutions, stable long-term funding, and democratic accountability.
Rather than treating nationalisation as the only answer, we should focus on the structural weaknesses that allowed the crisis to develop. Reform could look something like this:
1. Compulsory public listing.
2. A re-patratration of ownership: 75% minimum domestic shareholders.
3. Clarity of corporate ownership / governance.
4. A financial and policy environment that encourages long-term, stable funding from sources that are sensitive to public opinion
5. A simple and easily comprehensible method of assessing and publicising relative environmental performance.
6. Functional specialisation: separating water supply from sewerage and water treatment.
7. Regulatory specialisation: discrete and independent bodies for standards, permitting, monitoring and enforcement.
8. Democratically accountable catchment authorities that are independent of central government.
9. Complete transparency and real-time data.
10. Formalised 3rd sector and citizen science validation of standards.
Rivers do not care whether the water industry is owned by the state, by pension funds, or by listed companies. They respond only to whether sewage is treated properly, infrastructure is maintained, and the law is enforced. If we keep the debate focused on those outcomes, rather than on ideology, we might build a water system worthy of the landscapes it serves.
Nationalisation-lite – the longer version.
Taking its lead from last year’s hit drama Mr Bates Versus the Post Office, Channel 4’s Dirty Business has dramatised the malpractice of water companies and the incompetence of regulators, bringing public anger to a fever pitch.
From the town square— the X account of Hugh Grant, for example— comes the universal cry to ‘nationalise the water industry’. Nationalisation is, after all, what leading lights amongst the campaigners have been calling for. As Feargal Sharkey said to Toby Perkins MP, Chair of the Environmental Audit Committee, last summer 2025: ‘Right now, the vast majority of this industry, if not the whole industry, actually needs to be taken back into state control’.
Not nearly as prominent a voice as Mr Sharkey, I have nevertheless been campaigning for river health since the early 1990s. I co-authored the 2017 WWF report Flushed Away that helped bring this sewage scandal to a wider audience and stood with WWF’s brilliant Rose O’Neill and Kathy Hughes in a drafty corridor in Westminster, vainly trying to interest passing MPs. I should be delighted that a campaign once thought too esoteric for the public to care about (WWF hesitated over publication) has now hit the headlines. Finally, something might happen.
So, why do I feel uneasy about this war-cry of nationalisation as the answer? Reform UK has expressed support, and I suspect a more left-leaning Labour government might eventually do the same, particularly under pressure from the Greens. The current Labour government has taken state ownership off the table, for now, but you never know.
It’s not as if nationalisation would necessarily be the wrong answer long term, but quite apart from the fact that decisions like this shouldn’t be swayed by TV dramas, it feels in its current catch-cry form like too much of an easy, crowd-pleasing solution and one that won’t necessarily lead to cleaner rivers and seas.
Nationalisation has replicated and could very well again replicate the failings of the privatised system, under a different guise. Unaccountable corporate greed or unaccountable inefficiencies of state: take your pick. I’m more interested in the environmental outcome than thumbing the eye of capitalism: even if, in this case, the thumb may be deserved.
An equality of badness
There is mixed evidence, at least nationally, as to whether state-owned water industries lead to better environmental standards. True, beyond our shores the best countries for quality of wastewater treatment all feature various forms of municipal and state ownership. But here in the UK, where we appear constitutionally unable to run state entities as well as they do on the Continent, the pollution of our rivers and seas is as bad in Northern Ireland and Scotland (where water is state-owned) as it is in England and Wales.
Conversely, there is little evidence that private companies deliver better environmental standards either. This equality of badness may, in large part, boil down to cost. A clean environment is more expensive than a dirty one, no matter who is running the system. Over the last 50 years we have had underinvestment by the state followed by underinvestment by private companies. Is this because a world-class system would cost more than the British public is willing to pay? Has our industrial heritage driven too deep a wedge between people and their own landscape?
It can’t be an accident that the five best European countries for quality of wastewater services are motivated by the need to look after prominent and fragile ecosystems: Denmark, Finland, the Netherlands, Switzerland, and Austria. Of course, England’s population density is much higher— 450 per square kilometre— than all of those other ‘good water’ nations, bar the Netherlands (441). Wales is comparable with Denmark (150 v 140), Scotland (70) is someway between Finland (18) and Denmark (109).
Arguably, none of the above rivals started from such a low base. In the UK, river water quality is actually much better now than it has been for several centuries, especially when it comes to poo. Rivers like the Mersey once clogged with islands of industrial filth. When the SS Alice sank in the Thames in 1878, it was the sewage-infested water that killed people.
Designed to pollute
Worse, in the UK we have inherited a water system that is pretty much designed to pollute: Bazelgette’s combined sewerage was a massive improvement relative to the squalor of the mid 19th century, but time has caught up with it. We have plugged our modern lifestyles and the Augean oceans of poo 70 million people produce onto the nation’s river network via a system of pipes that must be flushed through with rainwater to remain functional. To keep even vaguely on top of this, our sewage systems need to have massive overcapacity and then must also stay ahead of the relentless creep of urban sprawl, paving, house building, car parks, retail parks, and roads that send more and more rainwater down the drain. Not to mention the 13 million extra bottoms relative to when the water industry was privatised and the more intensive rainfall patterns of recent years.
Now you see it, now you don’t. Our ‘combined’ sewage system has a fundamental flaw, mixing rainwater with sewage.
It is clear that privatised or nationalised, our industry needs investment: firstly to become fit for purpose with its existing, flawed (combined rainwater and wastewater) plumbing network and masses more investment than that to become fit for the 21st century. I wrote about a better system in my last blog: as far as possible we would take our rivers – certainly our most ecologically fragile rivers – off the supply and discharge network altogether. We would take the water in pipework to large, technically advanced treatment works close to the coast, with all the existing sewage works repurposed as stormwater storage tanks, like beads on a chain. This is all a long way off. For now we need to fix the holes in the roof. As we stand, water companies are looking to Ofwat to take the brakes off and provide a bit more investment through increased bills. Ofwat is looking to shareholders to fund their share. One option is unjust (in the historical context); the other is unlikely to happen.
But the fundamental idea of privatisation is not inherently wrong (nor nationalisation, for that matter), and need have nothing to do with the grottier ends of capitalism. Under any form of ownership, sewage infrastructure (if it is to be functional) requires a lot of capital, so much that it must be borrowed and the debt recouped over time through the bills charged to the beneficiaries of that infrastructure. The creditor (whether lending to the state, municipal utility or a private company) will therefore demand a reasonable dividend – they’re not going to invest for free – but they can at least be sure of a very reliable income stream, for people must use the loo in good times and bad.
I don’t see any way round that basic model. Either the government borrows the money and water infrastructure joins the queue behind all the other things the government must borrow money for (welfare, the NHS, education, policing, and defence). Or private companies, or some other institution, must borrow it. Independent funding is a feature of the exemplar publicly owned system I analyse below. A very large part of the protest against the current set-up in the UK is the apparent profiteering. However, a private entity can take various shapes and forms, can even be not-for-profit. Ideally to investors a water utility should look more like an income-yielding bond, rather than a geared-up cash cow.
Clearly, any set-up needs effective regulation, and clearly, our privatised industry didn’t get it. The problem was not so much the principle of privatisation but the way it was allowed through lack of effective regulation, environmental or financial, to metastasise into opaque financial wizardry.
How we got here.
The water industry was privatised in 1989. For a while, some extra investments were made: the shares floated at about £7 billion. Debt was written off and a green dowry added by the UK government to sweeten the deal. The infrastructure was in no great shape, and at the time, society had no real awareness of the degree to which releases of raw sewage were just part of what went on. In the 1980s, ‘Bocky Belly’ was an inevitable side-effect of swimming in the Frome downstream of Dorchester. I’m sure it was the same everywhere. People joked that you couldn’t drown in the Mersey, because you’d die from poisoning first.
Years later, it became clear that water companies really were routinely dumping raw sewage into rivers and seas (I took the photo at the head of the blog in 2007 and if you could smell it you’d gag), though still no one quite knew how much or how often. It was all just ‘flushed away’. In 2012, the much-unsung environmental hero Bob Latimer established through the European Courts(see para 7.) that according to the Urban Wastewater Treatment Directive – to which we were signatories – raw sewage should not be released other than in ‘exceptional weather conditions’: very much contrary to what was happening on his local river, the Whitburn.
A short while later, Fish Legal won a ruling that compelled water companies to comply with Environmental Information Regulations, and on the heels of that, WWF’s Rose O’Neill sent a Freedom of Information request to every water company, asking for details of their raw sewage spills. From memory, only one answered because only one had any idea. At the time, only a handful of sites were monitored at all. However, research by the South East Rivers Trust showed that the outfalls on the River Hogsmill in South London were spilling far more frequently than they had been designed to. And into a fragile chalk stream at that, the site of John Everett Mills famous painting of Ophelia. The spills were not related to exceptional weather.
If only that had been the worst of it. It took dogged campaigners like Phil Hammond and Ash Smith (as portrayed in the Dirty Business drama) to push more persistently and unearth a nationwide scandal of environmental malpractice driven by financial malpractice.
As Flushed Away identified, water company investment had stalled: that’s assuming it had ever really started. I remember we calculated that at the existing levels of investment in 2015 it would have taken 800 years to upgrade the systems. Ofwat – the financial regulator – set the price of water and was determined that it wouldn’t go up. Shareholders added little extra capital over time. Caught between the regulated price and income-hungry shareholders, water companies sweated sewage infrastructure to breaking point and the environment paid the bill. Debt accrued but flowed sideways into the pockets of shareholders, many of them overseas institutions that – one might argue – had little interest in the UK’s environment.
Clearly, Ofwat failed to curb any of this. So long as the price to the consumer remained low, the feeling was – so one must guess – that the greater good was being served? Besides, Ofwat at the time had no environmental remit, only one of cost to the consumer. However, the Environment Agency, whose job it is to police the industry’s environmental standards, must also have been asleep at the wheel. Monitoring of river water quality, of fish and invertebrates, all fell from regular to infrequent to scant in the early 2010s. Prosecutions for pollution were rare. Water companies were left to mark their own homework. From the outside it looked as if the environmental regulator was compromised by the economic implications of applying the law.
No wonder it all went wrong. Now, almost everyone agrees that structural change is needed.
Structural change
The Water Special Measures Act is this government’s attempt to address some of those failings. A lot of store is being set by the potency of other eco-populist catch-cries: bonus bans and criminal liability. I don’t know how effective these will be. Do we really think that water-company chief executives set out to break the law? Sewage infrastructure is not fit for purpose because of a problem decades in the making, now colliding with a level of public awareness far higher than even a few years ago. In AMP8 Ofwat has allowed for an unprecedented level of investment, very largely paid for by increased bills and only time will tell to what extent this starts to address the problem. It is only the start, however.
Looking at where we are and where we go next, the Achilles heel of nationalisation as an alternative is surely that two of the three institutions responsible for this poor situation are public bodies already. If Ofwat and the EA failed in their parts, why should we expect a public water industry to per se do any better?
The fact is we have had nothing like the reasonable investment model that we might have, where shareholders look not for creaming profits but for a modest, steady yield, offset by minimal risk. Instead, as research has shown, we have had net zero investment, debt has ballooned, and the money spent on infrastructure has all come from customer bills. According to a 2024 analysis by David Hall from the University of Greenwich – refuted by Ofwat and the industry – shareholder investment has effectively amounted to zero in real and adjusted terms between 1990 and 2023. At the same time, debt has ballooned from effectively nothing (the companies were debt-free at privatisation) to around £70 billion today. The total spent on infrastructure has been about £190 billion, but where did the money come from? Mostly from bills, according to David Hall, while all the debt has allegedly gone to pay dividends.
The difference between fair and what we got
The difference between a fair model and the model we got must surely be the difference between the dividends owners have paid themselves and a fair dividend yield on the investments made.
Against the £190 billion invested in infrastructure, £70 billion is modestly inline with a fair yield, equating to roughly a 2% pa dividend. However, if the £190 billion mostly came from bills, and a much lower sum was invested – and it appears to be true that there have been few injections of fresh capital over time – that £70 billion of dividend, rather than being a reasonable yield on £190 billion of investment, is a very generous yield on the amount invested at floatation. A fair yield on the £7 billion would have amounted to between £9 and £16 billion. (2.5% – to 3.5% over 35 years).
Meanwhile, according to critics, the companies have been leveraged with debt and bills have been higher than they should have been, in spite of Ofwat’s determination to keep them low.
All of which suggests that the system needs rebuilding. And yet while nationalisation might stem the bleed of debt capital to overseas ‘investors,’ would a nationalised version be any better from an environmental point of view? Let’s not forget the problems privatisation was supposed to address: regional water authorities disinclined to prosecute themselves for polluting waterways, chronic underinvestment (by government), creaking infrastructure, deteriorating water quality (a 1985 River Water Quality survey found a high % of sewage works breaching their limits), and very little appetite by customers to pay more for their water and sewage. The full English one might say, since we are so very good at polluting rivers. Plus ça change.
A paucity of ideas
The replication of these problems, whether under private or public ownership, probably explains the vagaries in the public debate. Beyond the easy catch-cry of nationalisation, there are few ideas, with the exception of those coming from Dieter Helm.
Alistair Carmichael MP, chair of EFRA’s Commons select committee, was tellingly non-specific when quizzed by Toby Perkins MP, chair of the Environmental Audit Committee. EFRA looked at ownership models to inform the Cunliffe report: the government had – at that time – ruled out state ownership. Nevertheless, said Carmichael, there is a fundamental truth that ‘you can have any model of ownership that you choose, but actually, if your industry as a whole has the wrong culture, if you lose focus on the customer service and environmental protection, then you’re always going to end up with bad outcomes.’
Instead of starting with the answer of ‘nationalisation’ and working backwards, we might do better to look at specifically what has gone wrong – a hurried privatisation that didn’t compel proper investment, opaque ownership regulations with no obvious accountability, a total failure of economic and environmental regulation, all built around a system of infrastructure that is conceptually flawed – and try to build a better answer from there. The clear evidence globally is that good environmental outcomes depend on satisfactory levels of investment, adequate regulation, and corporate governance, no matter how the water entity is owned.
Carmichael argued that regulation is what it boils down to, and many will agree with him. The regulator must keep the industry’s ‘feet to the fire,’ however the industry is constituted. Our regulatory system, Carmichael highlighted, is split between too many agencies and was not set up to cope with the labyrinthine financial structures the water companies fragmented into over time.
Hmmm. The single regional regulatory authorities that preceded privatisation had failed too. A 2020 Cambridge University Press study into drinking water standards found that public bodies commit significantly more treatment and contamination event violations and fewer reporting violations relative to private bodies, but also speculated that private bodies may exercise strategic underreporting. Which might lead one to the obvious conclusion that no matter what structure is set up, the regulatory side must be completely and effectively separate from the operational side and must not be captured by economics. Although the system has clearly failed, I have strong doubts that the state would have regulated itself any better.
In the UK, it has taken a third-sector form of inspection and regulation by protestors and NGOs to bring the issue to the fore. Any good system going forward must make room for a formal moderation by citizen scientists of the official marking system and the inclusion of that third-sector moderation in the regulation process.
Nevertheless, this economic capture is probably inevitable, to some degree, both of the state regulator and – surprisingly – the courts. In his book The River Pollution Dilemma in Victorian England: Nuisance Law versus Economic Efficiency, Leslie Rosenthal convincingly argues that in spite of the fact that British rivers have been protected back into the mists of time by Common Law and riparianism (the principle that owners of waterside property may make reasonable use of the water so long as that use does not inhibit the water’s quality and quantity for other users), a balance of convenience skewed towards economic efficiency and the greater common good has long overridden the common law in terms of practical application in the courts. Courts are unwilling, in other words, pedantically to apply the law if it causes economic harm (i.e. the cost of water going up) to a very large number of people, relative to the rights of a few.
It has made virtually no difference over time whether our rivers have been protected by riparianism, the 1876 River Pollution Prevention Act, the Prevention of Pollution Act of 1951, or the Urban Wastewater Treatment Directive. Economic efficiency will prevail, no matter how much a middle-class wild-swimmer or trout-angler (like me) may wish otherwise. Many critics insist that ‘we just need better enforcement,’ and they are not wrong, but the idea that courts alone can drive the levels of investment needed to build a world class system seems far-fetched.
Going Dutch?
So, what are the features of world-class water systems and how can we adapt them to our somewhat unique situation of inherited rust, too many bottoms, too much paving?
The Dutch system is widely regarded as among the best in the world. Drinking water is of a very high quality and is less expensive to the consumer than in the UK. Wastewater is treated to a very high standard too – 70% undergoes sophisticated tertiary treatment.
With the exception of the combined authority that serves Amsterdam (Waternet) the supply and treatment of drinking water is separated from the collection and management of sewer systems, which is in turn separated from the management of wastewater treatment plants. This allows for a high degree of specialisation.
Drinking water is supplied by regional non-profit and publicly owned utilities. Tariffs to the consumer cover costs, investment and maintenance.
Wastewater, on the other hand, is run under the Dutch water authority model, Waterschappen, comprising twenty-one decentralised public bodies (generally defined by geographical catchments) that form the main operational component of the water management system. Responsibilities include flood protection, water levels, water quality, and – critically – wastewater treatment.
Importantly, in terms of what we might learn, these regional boards are democratically accountable and are technically highly specialised and experienced. They are among the oldest democratic bodies in the country, originating in the 12th century and have acquired expertise over the centuries. They levy their own taxes and also have access to long-term financing through the publicly owned Nederlandse Waterschapsbank (NWB Bank), which provides low-cost loans for public infrastructure. This financial autonomy ensures stable funding for long-term water management projects and supports the sustainable operation of the Dutch water governance system.
The cornerstones of the managerial system are, therefore: functional specialisation, decentralised governance, democratic legitimacy, and financial independence.
Regulation
That’s all very well, but who holds their feet to the fire? In the UK, Alistair Carmichael MP pointed to the ‘littered landscape’ of Ofwat, the Environment Agency, the Office of Environmental Protection, the Drinking Water Inspectorate, as part of the problem in holding the water industry to account. ‘You know, everybody’s got a bit of skin in the game, and then when things start to go wrong, it’s too easy for somebody to say, well, that’s not really our job, it’s theirs.’
Countering the Carmichael viewpoint, the Dutch system is radically decentralised with tiers of overlapping regulatory responsibility. Water boards must answer to the National Inspectorate (ILT), Provincial permitting authorities, the National Water Manager Rijkswaterstaat, scientific oversight (RIVT) , democratic elections, the courts, and effective public scrutiny.
Carmichael’s thoughts presaged those of government, however. In June last year the environment secretary Steve Reed announced that Ofwat would be abolished and a new super regulator would take over from Ofwat, the EA and the drinking water inspectorate. ‘A single, powerful regulator responsible for the entire water sector will stand firmly on the side of customers, investors and the environment and prevent the abuses of the past’.
The Dutch model suggests that overlapping or even split regulation was not the problem. Quite the contrary, it has been a strength. The problem in the UK is buried in the optimism of Steve Reed’s quote. A conflation of the interests of customers, investors and the environment is exactly what Ofwat and the EA got so wrong. The interests of customers, for example, are precariously balanced around the question of cost. A single, super regulator sounds very grand but at the coal-face it’s always a trade-off. Resolving these competing interests is not at all easy in theory, let alone practice. I’d place more faith in discrete and clearly defined areas of regulation with watertight barriers around any possibility of regulatory capture.
For a long time, for example, the thought was that a major barrier to progress in curtailing the over-abstraction of rivers, was the water company licence of right to abstract. What we needed, we all thought, was the ability to remove those licences when it is clear a stream is being damaged, without the need to compensate the water company. We now have that ability, but vanishingly few licences have been revoked. The burden of proof has now moved to slam-dunk, plank-in-the-face evidence of damage, beyond a dry riverbed and dead fish, mind, because a dry riverbed and dead fish might be down to natural causes. The EA has long been caught between protecting the environment and permitting activities that damage it. This is an impossible situation. So long as the EA is saddled with schizophrenic regulatory tasks it will struggle to do its job properly.
A super regulator may well struggle with the same issue of irreconcilable interests. And when it does, money will win, just as it does now.
Nationalisation-lite.
So, if and when the regulators fail to ‘hold feet to the fire,’ – which they will from time to time, even in a perfect world – we come back to the question of governance and accountability. Something that is so clearly transparent in the Netherlands. How directly publicly accountable are the ownership structures in the UK?
Not very much, is the answer. Only three out of nine (South-West Water, United Utilities, and Severn Trent) are publicly listed. The majority of the shares in each of these – 60% to 70% – are held by UK investors, mostly pension funds, insurance companies, and retail investors. These institutions, which will all have active Environmental, Social, and Governance (ESG) departments, should in theory be more sensitive to UK public opinion than the complex and opaque smorgasbord of private equity, foreign sovereign wealth funds, foreign pension funds, and asset management companies that own the other six water companies.
Does this difference in ownership structure translate across to differing levels of environmental performance? Maybe. Severn Trent was the only company with a top-of-the-class rating in 2024. However, Wessex Water appears to be the water company with the best environmental record over time, and yet it is majority-owned by the Malaysian infrastructure conglomerate YTL.
Even so, clarity and accountability could and should make a difference.
It is standard practice globally that companies of particular strategic importance to a nation – airlines, for example, telecommunications, energy – must have a minimum percentage of domestic ownership. Delta, American Airlines, Air Canada, and Qantas must all be owned by a minimum of 51% domestic shareholders. In Canada and Japan, foreign investment is limited to 20% of telecom operators. Both Canada and Australia edict that domestic pension funds must hold majority shareholdings in strategically important companies. The reasons are obvious but include security and economic sovereignty.
Why should water be any different? If all the water companies were by law publicly listed on the UK stock exchange, with a maximum foreign ownership capped at, say, 25%, it would surely lead to more clarity and therefore accountability in their governance. Even better if the financial system and policy environment strongly encouraged investors such as domestic pension funds to own large shares of this national infrastructure. Pension funds have long investment horizons, a need for steady income, and an ability to invest very large sums of money on fair terms. UK pension funds and their active ESG departments should be much more sensitive to public opinion than opaque overseas financial vehicles.
Especially if we could also create a clearer portrayal for customers of ownership associated with relative environmental performance. Why shouldn’t every water bill list who the primary shareholders of that company are? And, why shouldn’t every water bill include the environmental performance rating of that company over the previous one year and five?
The Environment Agency produces a star rating every five years. But few people know about it and it is a bit too esoteric for customers in my view. Customers need a little blue drop or a little brown drop. And they need this printed prominently at the top of the water bill alongside the company logos and a list of who the primary UK-based shareholders are. I can see the likes of Legal & General very much preferring to see their names printed under the blue drops, not the brown.
I have no idea how legally tricky it would be to mandate this public listing, to mandate a minimum % of UK ownership, and enact the policies that would encourage the right kind of investor. But I suspect it would be easier, and less expensive for the government than nationalising the industry and less likely to spook the markets, to use an overworked phrase. A system such as this would achieve a level of nationalisation-lite and powerfully add to our arsenal of regulation the leverage of corporate sensitivity to public opinion, curtailing the financial shenanigans and driving stronger environmental stewardship over time.
Ownership alone will not clean our rivers.
It is tempting, when a system fails so visibly, to reach for the most dramatic solution available. Nationalisation has the virtue of clarity and the emotional satisfaction of redress. After decades in which the public has watched sewage pour into rivers while dividends flowed out to investors, it is easy to see why the call resonates. However, the failures we are dealing with are systemic. They include poorly designed privatisation, unaccountable corporate ownership, and a regulatory regime tasked with divided and irreconcilable priorities, that was under-resourced and in places captured by the very economic constraints it was meant to police. Changing the ownership without fixing those structural weaknesses risks simply recreating the same problems in a different set of clothes.
What ultimately determines environmental outcomes is more practical: sustained investment, transparent governance, and regulators that are genuinely independent and empowered to enforce the law. Countries that succeed at managing water tend to combine these features regardless of whether their systems are public, private, or hybrid.
That is why a better path may well lie somewhere between the slogans. A system that makes ownership transparent, encourages long-term domestic ownership and investment, aligns shareholder incentives with environmental performance, and strengthens independent environmental regulation could deliver many of the benefits people associate with nationalisation without the financial and political upheaval of full state takeover.
Call it nationalisation-lite if you like.
1. Compulsory public listing.
2. A re-patratration of ownership: 75% minimum domestic shareholders.
3. Clarity of corporate ownership / governance.
4. A financial and policy environment that encourages long-term, stable funding from sources that are sensitive to public opinion
5. A simple and easily comprehensible method of assessing and publicising relative environmental performance.
6. Functional specialisation: separating water supply from sewerage and water treatment.
7. Regulatory specialisation: discrete and independent bodies for standards, permitting, monitoring and enforcement.
8. Democratically accountable catchment authorities that are independent of central government.
9. Complete transparency and real-time data.
10. Formalised 3rd sector and citizen science validation of standards.
Above all, the debate should not become a proxy war over ideology. Rivers do not care whether the water industry is owned by the state, by pension funds, or by listed companies. They respond only to whether sewage is treated properly, infrastructure is maintained, and the law is enforced. If we keep our focus there — on the ecological outcome rather than the ownership model — we might build a water system worthy of the landscapes and people it serves.
Back in the summer we received a letter from Defra and Minister Hardy about the government’s plans for chalk streams, after they abandoned the long-promised chalk streams recovery pack. I wrote about that letter HERE.
Twice recently I’ve been asked to summarise what could be done that would be ecologically effective and cost-effective. As ever, it’s the cost of protecting nature that sets the pace. The answer is no more than I have written about before, because the ideas were always cost-effective. But perhaps if I express it all as a very simple, rounded package that could be started immediately in at least one – if not two – major catchments: London’s Rivers Colne and Lea. It goes like this:
Re-naturalise flows by relocating abstraction
Take the chalk streams off the sewage discharge system and repurpose the small sewage works as stormwater storage
Re-meander the rivers, especially in public spaces, and in so doing boost biodiversity, flood management and carbon sequestration.
In my view this would be a total no-brainer and I can’t understand why we’re banging on about water company bosses doing jail time, when we could actually get on with fixing things.
Recovery of healthy flows
It starts with Chalk Streams First. A very simple and cost-effective way to re-naturalise flows in those very heavily abstracted chalk streams around London and Cambridge. Chalk Streams First relocates abstraction from upper catchment groundwater to lower catchment surface flow and allows the chalk stream first use of the water, all without a significant loss to public water supply. It’s chalk stream cake-ism.
An ongoing process called the National Framework (NF) has identified the deficits to good ecological flow in all of England’s rivers. The water companies, NF regional groups and Ofwat RAPID are developing multi-decadal strategies for water supply, security and environmental protection and restoration, including addressing those deficits to good flows. The smorgasbord of options at their disposal includes reservoirs, pipelines, desalination plants, recycling etc. We should see Chalk Streams First as another major one of these “strategic options”.
Conceptually, CSF, works by greatly reducing groundwater abstraction in the upper reaches of chalk streams. This leads to flow recovery, as the groundwater bounces back up. Generally speaking around 85% of the reduction recovers to the river as surface flow (some is lost as aquifer throughflow and some as evapotranspiration). This re-naturalises the flow in the chalk stream and the extra flow can be taken as surface abstraction much lower down the river system from the reaches where the ecology is less flow dependent. The water is then stored in reservoirs and piped to the places formerly supplied by the groundwater abstraction.
Dorset’s River Piddle is one shining example of what happens when flows are re-naturalised. This exact spot used to dry up regularly when abstraction was at its peak in the 1980s
There is a caveat: the flow recovery is not evenly spread through the year. It is much higher in winter, well over 100%, and commensurately lower in the summer. This leaves you with a summer shortfall, hence the need for a reservoir. In times of extreme drought, the flow recovery would be minimal and public supply threatened.
Ensuring public water supply in droughts
This is where you bring in the concept of a public supply groundwater back-up. Counter intuitively, it is during the drought that you draw on groundwater abstraction to make up the shortfall. Essentially you temporarily mine the aquifer (taking water from aquifer storage in the midst of the drought) and use the chalk streams as the means of delivery from the point of groundwater abstraction to the point of surface water abstraction. The scheme runs for just long enough to get you through the drought.
This actually protects the chalk streams with boosted flows in the drought, though this protection is a bi-product, not the purpose. It leads to slower aquifer recovery in the following winter and perhaps lower than normal flows the following year. In spite of that, the chalk streams flows throughout are still much better than they would be under our existing, chronic abstraction scenarios. A scheme like this already exists: the West Berkshire Groundwater Scheme run by Thames Water. It has been needed only a couple of times in the past 25 years and even then only briefly.
Essentially, Chalk Streams First allows us to re-naturalise flows in chalk streams without a significant loss to public water supply.
Using Chalk Streams First to solve our sewage crisis
Isaac Walton’s beloved River Lea doesn’t really exist upstream of Luton sewage works. Is there a future world where it meanders healthily through Leagrave Park, while the sewage is piped down the valley to much more technically advanced treatment works?
There’s ANOTHER dimension to the Chalk Streams First idea that has been unsung thus far, but which could be THE answer to the 24/7 inflow of nutrient rich and scantily treated sewage water to the upper reaches of our chalk streams from sewage works that are otherwise very expensive to upgrade. The brutal truth at the moment is that many to most of the chalk streams in heavily developed catchments actually need sewage discharges to meet flow targets. The Lea doesn’t really start life until the Luton works outfall. But re-naturalised flows driven by the aquifer would mean our streams are no longer dependent on sewage discharges for flow.
This will give us a solution to the thus far impossible issue of getting cost-effective phosphorus stripping to small-scale sewage works in the upper reaches of rivers. The water industry has actually done a lot to reduce phosphorus discharges, but the laws and incentives have been constructed in such a way as to drive all the investment to very large treatment works. The smaller works get left behind, even though they create the greatest problem in the most ecologically sensitive places.
Chalk Streams First means we could take our chalk streams off the water supply AND discharge circuit altogether. If we no longer need discharges for flow, the small sewage works that currently exist can all be connected and piped down the valley to larger works. Each STW that comes off-line as a treatment works can then be repurposed as storm storage facility, providing a series of buffers in the system.
If flows were re-naturalised we would no longer need sewage discharges to meet flow targets in our chalk stream headwaters and upper reaches. We could take our chalk streams off-line and treat all the water in larger works further down the valleys. Small sewage works could be re-purposed as stormwater storage areas, placing buffers in a daisy chain down the system.
Re-meander the streams, increase biodiversity and store carbon
Finally, you add to the above the comparatively cost effective physical restoration of streams that have been greatly modified over the centuries. Natural chalk stream floodplains are potentially vast carbon sinks, but we’ve dried them out and corralled our chalk streams into canalised straitjackets. I’ve just completed a raft of proposals along these lines for chalk streams in Norfolk and as part of that process reviewed the costs per mile of large-scale re-meandering and floodplain restoration. The numbers – £100 to £350K per mile – seem high, until you compare them to other numbers and reflect on the way in which restoration on this scale adds up to genuine and massive gains in biodiversity, natural flood management and carbon capture. By comparison, it costs well over £2 million to resource a 1-megalitre per day water supply.
Put those three measures together and you have the chalk streams of the future, once we get a government sensible enough to see the potential.
We live in hope.
This lovely image by photographer Charlie Hamilton-James is of a re-meandered chalk stream in Norfolk. There’s no reason why we shouldn’t roll out this sort of stream and floodplain recovery in public spaces and parks in the chalk landscapes all round the Chilterns and London, boosting biodiversity, flood resilience and carbon sequestration.
Pictured above: sewage? No. Road run-off from a mid-summer rain-shower.
You may remember Sophia’s petition for the protection of chalk streams, which quite easily surpassed the 10,000 signatories needed to elicit a letter from Defra, if not enough to trigger a debate in Parliament. However, a debate on river health was had recently (29th January) and chalk streams were mentioned several times.
The text of that debate can be found by clicking this LINK
I probably ought to let you all judge for yourselves what it amounts to or signals.
Personally, I have reservations about how easy it is now to dump blame on the water companies. Not that they don’t deserve a great deal of blame, but the parlous state of our rivers is not only down to water company malpractice. Our laws are at fault. Our regulation is at fault. Our pricing of water is at fault. Cheap food is at fault. Highways maintenance is at fault. Flea treatments are at fault. How much water we all use is at fault. Wet wipes are at fault. The ever increasing size of modern tractors is at fault. Our historic inheritance of mills, canalisation and dredging is at fault. The last three, historically the most remote, are in combination with all the above present day ills, the most significant impacts of all and yet receive virtually zero attention. Having said that, Minister Hardy, did at least extol the virtues of re-wriggling rivers.
Capping water company director’s bonuses might well be one in the eye for some of the folk who should be held to account, but I’m not sure it’s going to really do much to restore our beleaguered rivers more generally or chalk streams in particular.
For that we need some forensically focussed realignment of environmental law, economic drivers and regulation aimed not just at the water industry but at all the pressures that hold our rivers back.
There’s much in Minister Hardy’s final statement to indicate a general commitment to the above.
“Restoring the health of our rivers is fundamental to safeguarding nature, supporting resilient communities and securing our water environment for generations to come. The Labour Government are committed to delivering the most comprehensive programme of reform ever undertaken. It involves strengthening regulation, boosting enforcement, investing in innovation, supporting local partnerships and empowering farmers, land managers and water companies to play their part. From national action on agricultural pollution and chalk stream protections, to ambitious local projects in South Dorset, we are driving real, long-term improvements. Together, those measures demonstrate our unwavering commitment to cleaner water, thriving habitats and a healthier natural environment across England.”
The devil is in the detail, however, and in the end it comes down to that which can be quantified. How much less water will be abstracted from our chalk aquifers? By what date? How will we prioritise abstraction reduction so that we don’t repeat the mistakes of the way we have prioritised phosphorus reduction (ie driven by economics rather than ecological benefit)? Where will the replacement water come from? Will we now, finally, incentivise phosphorus reduction from tiny sewage works in headwaters and tributaries? Exactly how will we do that? Will we persuade or incentivise farmers to adopt better ways to keep soil on their land? Exactly how? Will local authorities adopt less damaging practice in local road maintenance programmes? When by? Etc. Etc.
Specific actions. Specific numbers. Specific dates. These are the things we tried so very hard to get into a Chalk Stream Recovery Pack. Without them it’s all so much fish and chips wrapper.
Dumb, damaging and pointless drainage: one of the many things that impact chalk stream health.
Ali Morse – chair of the CaBA chalk stream group – has written a letter (see PDF below) to Minister Emma Hardy (pictured above with the Yorkshire Wildlife Trust beside the Foston Beck) encouraging her to support measures to restore and protect chalk streams, but also expressing disappointment that the water White Paper and NPPF have not given us the promised assurances that chalk streams will get the “recognition and protection they deserve.”
Some time before the last election – and sensing, without any great gifts of foresight, a change of government – I spoke with Daniel Zeichner, the Cambridge Labour MP, about how important it would be to continue our chalk stream restoration work beyond the election, to harness the momentum gained from a strategy that had been signed up to by all sides. I might have been naive (though not as naive as those firebrands who correlated conservation nirvana with a change at Westminster) but Zeichner agreed wholeheartedly. He said that Feargal Sharkey – who was vigorously campaigning for Labour at the time – would hold them all to account if they didn’t do something.
And yet in spite of all that, the responses of the new(ish) government to repeated pleas for the greater protection of chalk streams have been underwhelming, to say the least. Having filibustered the progress of Minister Pow’s promised Chalk Stream Recovery Pack, Defra used the election as a means to nudge the pesky document under the carpet and finally to bury it altogether.
But when I met Minister Hardy last summer on the banks of Yorkshire’s Foston Beck, I met someone who I felt was motivated – as Minister Pow had been – to help chalk streams. She seemed genuinely keen to listen and help. Genuinely flabbergasted by some of the anomalies in existing environmental law that, for example, drive ever more expensive sewage treatments to works where the benefit to wildlife is minimal, while ignoring those places that need it most. But I also sensed a hesitancy to commit. Having worked for a year with Defra trying to midwife the Recovery Pack I knew why. Trying to persuade that unelected part of government to do anything differently is like pushing water uphill, whether you’re a Minister, an eNGO or individual citizen.
As Ali points out in her excellent letter, during the passage of the Planning and Infrastructure Bill we saw consistent and strong cross-party support for measures to protect chalk streams. We heard ministerial assurances from the despatch box that effective chalk stream measures would be included in upcoming policies.
But we haven’t seen much of substance, thus far.
No surprise, perhaps. There is no Damascene moment in conservation. I’ve been banging on about chalk stream protection since the dark days of the late 1980s when abstraction was at its peak, when cattle poached the riverbanks to bits, when land drainage engineers ruled the waterways, when zero phosphorus was removed from sewage and when “restoration” of rivers was an eccentric form of guerrilla resistance. Things are better than that now, though sometimes it may not feels as if they are.
To that end, Ali has extended to Defra the hand of continuing cooperation backed by the wealth of expertise now assembled under the umbrella of the CaBA chalk stream group, very ably managed by Alison Matthews. And I have invited Minister Hardy to come and visit the River Chess to meet with the River Chess Association and the Chilterns Chalk Stream Project and see first hand how collaboration and persistence can bring about the recovery of a chalk stream.
Chalk-Streams 