Could this be the swift solution to Cambridge’s water supply crisis?

The region’s pressing need for stable water resources could be met quickly and affordably with a new system of reservoirs on agricultural land, according to a trio of Cambridge figures.

They say their scheme could meet the “incremental annual growth of houses in Cambridge for the next 15 years, until an interim link from Grafham Water in 2032 is installed and a major statutory reservoir delivered at Chatteris in around 2040”.

And they estimate it could cost just £80million to deliver the seven new reservoirs between Waterbeach and Downham Market to add to the seven that already exist, along with a new water treatment works to serve them.

Each mid-sized reservoir could comfortably supply enough water for 7,000 people each, and would cost about £2m-3m each.

The concept has been put forward to The Cunliffe Review, the independent commission on the water sector regulatory system, by:

- Matthew Bullock, a former banker, ex-master of St Edmund’s College, Cambridge, and founder of academic and business membership organisation Cambridge Ahead;
- Prof Peter Landshoff, a former professor of mathematical physics at the University of Cambridge and member of the board of the local nature partnership Natural Cambridgeshire; and
- Prof David Newbery, emeritus professor and director of The Energy Policy Research Group at the University of Cambridge.

They say: “Our desire is to sustain the high economic growth that the Cambridge region has experienced, and which is likely to continue, to address this lack of stable water resources and to moderate the impacts that this is having on nature in the region.”

The plan would also “address the known impact of carbon emissions arising from the progressive drying of the lowland peat soils in the Fens” which threatens food security, they add.

The region’s lack of water resource is seen as one of the major barriers to growth in the Cambridge region, with an over-reliance on water from the chalk aquifer causing precious chalk streams to dry up.

Anglian Water is planning a reservoir at Chatteris to address the issue, but that will take until at least 2036 to complete. An interim measure – piping water to Greater Cambridge from Grafham Water – will take until 2032, while the impact of proposed demand management measures is highly uncertain.

“In the longer term, Water Resources East are also forecasting that neither the Grafham or Chatteris options will be sufficient and that up to half of the Eastern Region’s water will need to come from desalination,” say the trio. “Even if eventually successful as to timeliness or volumes, these plans will still limit Cambridge’s growth substantially in the interim and will threaten nature and the economic life of the Fens.”

While Cambridgeshire is in the driest part of the country, with the lowest rainfall, the authors point out that recent records show “no shortage of water running through the region over the course of a year”.

They tell the review: “There are three major rivers that run across the county – the Nene, the Ouse and the Cam. The Nene and the Ouse are long rivers, drawing water from the Northamptonshire Cotswold hills and Bedfordshire plateau, before traversing the county; the Cam draws its water from chalk aquifers and streams along the local East Anglian Heights, part of the Chiltern hills.

“All three rivers deliver substantial excess water during the winter half of the year.

“Despite this annual excess, the current water management system does not encourage investment in water storage, and it is the lack of storage which is the cause of the current shortage. Indeed, significant efforts have to be made in the region to pump excess water out into the North Sea, at great cost to Fenland farmers and ratepayers, only then to restrict water supplies for all users during summers. And there are active discussions about whether desalination plants will be required to address future shortages in some areas, rather than encouraging more extensive storage.”

They point to structural issues in water management for this illogical situation, with water having no “realisable economic value”.

“All physical water resources in the country are managed by the Environment Agency (EA), an agency under Defra, which controls the movement of water – man-made and to a degree natural. EA does not have any ownership of water.

“Despite longstanding common law rights, riparian rights and ownership of private water bodies are vested in individual landowners, but through EA’s exercises of the control of movement in the form of abstraction licences, ownership and transfer rights of water itself are essentially neutralised to minimal levels,” they say.

And while the Environment Agency is focused on tackling droughts, floods and pollution, using public money, it is “ignoring the ability to mobilise private investment based on encouraging a more active water economy”.

Currently, Internal Drainage Boards (IDBs) are limited in power to manage water levels in drains and ditches. But they could play a much more active role in water management, the trio argue, as their equivalents do in the Netherlands.

Farmers can play a key role in developing the wider water sector too, they tell the commission.

“The volume controls run by the EA effectively limit the upside value of the water and thus reduce any normal incentives to invest in water storage. As a result, the wider water sector is economically substantially undeveloped. Despite all these disincentives, farmers have increasingly had to invest in their own mid-sized reservoirs out of their own resources, but these have only been created as an insurance against climate change variations which are damaging their crops,” the authors say.

Creating mid-sized agricultural reservoirs would be far easier than the kind planned by Anglian Water, they point out, as they would be dealt with by local authority planners rather than at government level and could be completed in three years.

By contrast, the Development Consent Order process for a statutory reservoir now takes more than 12 years.

“Access to this additional water would be provided by a consortium of large farmers, held in a network of mid-sized agricultural reservoirs, based across the 41,000 hectares in the South Levels catchment of the Ely Group of Internal Drainage Boards, running north from Waterbeach to Downham Market,” they suggest.

“Currently the farmers already hold more than 5.4 million cubic metres of water in seven reservoirs, equivalent to about 10 per cent of the Chatteris reservoir capacity. These are currently used to ensure crop irrigation in summer months, but if the farmers were to fund seven further multi-use reservoirs, these 14 reservoirs would be more than sufficient to meet the incremental growth in the Cambridge region.”

Each reservoir could hold around 450,000 cubic metres of water.

“The ‘raw water’ would be taken primarily from winter surface water and stored, before progressively decanting into the Internal Drainage Boards network of ditches, drains and rivers within the South Level Catchment to move the water upstream to a balancing pond upstream on the Cam at Waterbeach.

“There the wholesale water would be delivered as ‘Waterbeach Raw’ to a new water treatment facility, thereby giving access to the potable water network for the city,” they write, suggesting that the £40m cost of this new facility “would be insignificant in the context of sustaining the city’s continued growth”.

They add: “The transfer of water between reservoirs to Waterbeach would be managed by the Ely IDBs, under supervision by EA. The balancing pond capacity already exists but would need to be increased progressively.

“The reservoirs would be built on the farmers’ land and planning permissions for additional mid-sized agricultural reservoirs would be required from East or South Cambs [district councils] on current arrangements. The new water treatment facility would need planning consent and the treatment of the water would require permission from the Drinking Water Inspectorate. The raw water offtake would be sold wholesale.”

And they tell the review: “As of now, the capacity of existing reservoirs built by farmers for their own purposes already amounts to more than 15 years’ projected needs. Additional reservoirs could be phased as growth unfolds.

“In the longer term, it is highly probable that this supplementary supply would become a permanent supplement.”

Asked about the possibility of agricultural chemicals running off into farm reservoirs, Mr Bullock told the Cambridge Independent that as the South Level land is predominantly peat, fertiliser is not needed. An Environment Agency consultant is also testing the quality and volume of water to assess the project’s feasibility, he added, but they have already confirmed the water would not be affected by the ‘forever’ chemical PFAS.

The water treatment works would then ensure any water was fully potable to Drinking Water Inspectorate standards, he added.

The Cunliffe Review into the water sector and its regulation was launched by the government last October and is due to report its findings this year.