What is happening at Oughtonhead Springs?
Given the prevalence of pollution incidents, supply outages and what appear to be undeserved rewards to water company executives and shareholders, it’s hard to say anything positive about water companies without opening oneself to charges of naivety. Nevertheless, I might have some observations to help restore the balance.
In 2023 we invited Sarah Perry, River Catchment Coordinator of the Herts and Middlesex Wildlife Trust, to speak about chalk streams at our AGM. Unfortunately, due to internet problems, Sarah’s talk was something of a gallop, but she did provide us with her slides, which are accessible on our website1, and which provide some useful background.
Chalk rivers are very rare globally. There are well over 200 of them, and the majority are in the southeast of the UK, an area of relatively low rainfall when compared with other parts of the country. Hitchin is surrounded by a number of springs. By the time water emerges from a spring, such as at Oughtonhead, the rain has permeated through the soil and into an aquifer in the chalk. The slight acidity the water possesses due to the carbon dioxide in the atmosphere is neutralised by the chalk. This creates unusual conditions supporting diverse communities of organisms not often found elsewhere. The health of the Oughton is doubly important because it helps to maintain the wetland of Oughtonhead Common – the largest area of wetland in Hertfordshire – which is a Local Nature Reserve, owned and managed by North Herts Council. On the northern side of the river is what, until recently, was the Middlesex Wildlife Trust’s Oughtonhead Nature Reserve. The management of this has now reverted to the landowner.
Affinity Water has a long-standing abstraction licence allowing it to take up to 450 cubic metres per day from a borehole in the aquifer about 200m west of Oughtonhead Springs. From 2013, nitrate levels were too high for the water from this borehole to be fit for use as drinking water, so there has been no abstraction, at least for most of the period from then until the present. This has led to further pressure on other sources in the Hitchin area. Doubtless the problem has been exacerbated by the number of new housing developments in recent years, and the large development at Highover Farm will increase demand further. Water companies have an obligation to supply water and sewerage services for new developments, so it was to be expected that Affinity Water would attempt to obtain planning permission for a denitrification plant at some stage. An application from the water company2 in 2021 was permitted in June 2022.
In preparing this article, I have struggled to find clear understandable information to demonstrate that Affinity Water’s investment is bringing a benefit to the River Oughton and its associated nature reserves. It appears that I am not alone. Apart from the Wildlife Trusts, numerous organisations are keen to preserve and enhance chalk streams, including the water companies. However, according to the Chalk Stream Restoration Group’s Annual Review of its Restoration Strategy for 2024/253, first published in 2021:
“There has been substantial investment by the water industry in the period 2020-25 and record levels of investment are planned for the next 5-year period. Despite that, it is often hard to report what the benefits of that investment have been as information is not presented in an accessible way or is simply not available.”
Perhaps one way in which Affinity Water invested in chalk streams is via an Abstraction Incentive Mechanism (AIM), the most recent report4 of which covers the years 2023-24. The aim of this mechanism is to encourage water companies to minimise extraction at times of drought from vulnerable sources like that at Oughtonhead. As I understand it, some of the water that would have been used to supply consumers can be diverted into the river to enhance flow and to avoid the possibility that the wetland will dry out. This has been doubly important following the collapse of the weir at Westmill in 2022, which increased flow of water downstream of the mill, thus raising the possibility that the wetland would become drier5.
Reading the AIM report, I find it hard to say whether water from the borehole was being used in this way (which the report calls augmentation) when the report was compiled. Surely it would be possible to say when augmentation happened, for how long and what proportion of the daily 450 cubic metres of water was diverted into the river. I am not even sure whether the denitrification plant is operating to enable the Oughtonhead borehole to supply drinking water yet.
In the absence of clear information, I can only report what I have seen for myself. The denitrification plant appears to be complete, but it is impossible to tell whether it is fully functioning, and I have never been able to find anybody there to ask. Affinity Water is attempting to create an ‘area managed for nature’ to the north of the denitrification plant which is encouraging such species as hawthorn and includes bird and bat boxes. Unfortunately, it is possible for motor cyclists to gain access to the area and on at least one occasion in February, several motor cyclists were in the process of churning up some of the grassland there. Water monitoring points have been installed – for example, one in the wetland next to the track alongside the Oughton to the east of the pool known locally as The Chalky, and another in the field to the west of the Temple End pumping station on the road from Charlton to Preston. I think the purpose of these is to assess the water level in the aquifer at these points, but am not sure. On three occasions during the recent dry period, I have noticed unusually large volumes of water welling-up from the normally placid Oughtonhead Springs. I have never seen this before.
A few weeks ago, I spoke to a hi-vis-clad man who was floundering around in the water trying to measure the flow at the spring in its placid phase. Repeated efforts were meeting with failure (the flow was very small) and he was attempting to get some sort of reading by corralling the water by means of branches which were lying around. His attempts did not seem very scientific, and he didn’t seem to know very much about Affinity Water’s activities, the river or the status of the wetland.
If it is the case that flow in the river is being bolstered by water diverted from the domestic water supply, that must surely be a good thing for the health of the river and the nearby wetland. As an example of the effectiveness of Affinity Water’s attempts to protect the wetland and the river, I am forced to agree with the Chalk Stream Restoration Group’s conclusion that it is unclear what the effect of Affinity Water’s investment actually is. It would be good to have information that is current, detailed and authoritative, yet easy to understand showing the anticipated benefits that this investment should bring.
- Chalk River Conservation; working with landowners on a catchment scale:
https://www.hitchinforum.org.uk/wp-content/uploads/2026/05/Chalk-River-Catchment-Conservation-Hitchin-Forum-Nov-2023.pdf - Minutes of North Hertfordshire’s Planning Control Committee meeting Thursday 23rd June 2022:
https://democracy.north-herts.gov.uk/mgAi.aspx?ID=12977 - Chalk Stream Restoration Group’s Annual Review of its Restoration Strategy for 2024/25:
https://catchmentbasedapproach.org/wp-content/uploads/2021/10/CaBA-Chalk-Stream-Annual-Review-Executive-Summary.pdf - Affinity Water: Abstraction Incentive Mechanism- Methodology and Abstraction in 2023-2024:
https://www.affinitywater.co.uk/docs/reports/2024/AIM-performance-2023-2024-annual-report.pdf - Oughtonhead Common Greenspace Action Plan 2022-2027:
https://www.north-herts.gov.uk/sites/default/files/2023-01/Oughtonhead%20Common%20GAP%202022-27%20Final.pdf