A rare and globally scarce lowland river fed by underground water, the River Ems chalkstream flows from its source in West Sussex to Emsworth before crossing into Hampshire, where it empties into Chichester Harbour. Along its short 9 km range, it faces a disproportionate number of pressures, putting the river and its wild fish populations at risk.
National conservation charity WildFish is conducting interviews with some of its volunteer citizen scientists who take part in the charity’s river monitoring programme, SmartRivers. Sandy Galloway, founding member of Friends of the Ems and the SmartRivers group lead, answers questions from WildFish as they journey down this rare and diverse chalkstream, unpicking the threats and discovering why this river – like so many across the country – urgently needs better protection.
WildFish: The Ems is your local river, one you fight hard to protect. Describe how we would find it today?
Sandy Galloway: The Ems is a complex and heavily-modified watercourse.
As it meanders through West Sussex from its source at Stoughton, several man-made barriers obstruct its flow. Historically, the river supported at least four, possibly five watermills, extensive water meadows and three watercress ‘farms’, as well as trout and eel fisheries.
For perhaps a thousand years people have altered the River Ems to meet the needs of their own time. Medieval communities harnessed it to grind grain. Farmers diverted it across water meadows. Growers channeled its clear chalk water through watercress beds. Industry impounded it to power mills serving a port and the navy. A population increasingly drew water from the aquifer beneath it.
Wildlife is in decline along the river. Worryingly, data from Professor Nigel Holmes suggests an increasing loss of biodiversity. Particularly concerning is the 75% decline of the previously resilient brown trout population, and a significant recorded fall in eels and bullheads.
WildFish: As someone who spends a great deal of time understanding the river, what do you think are its biggest threats?
Sandy Galloway: With the River Ems, we have learnt that when we interfere with flow the river becomes increasingly vulnerable.
River barriers are a significant concern. There are several artificial structures designed to control the flow of the river including dams, weirs, sluices and gates – all structures developed to divert, contain flow and harness its energy.
My experience with the Ems has also taught me that some barriers are more subtle and not cast in concrete or constructed with wood, like the over-abstraction of water. These are rapidly appearing with changing climate, resulting in higher temperatures and changing rainfall patterns.
On the Ems, over-abstraction has been a significant obstruction to the normal movement of the river’s wild fish populations.
WildFish: Thinking about barriers, a notable cause of wild fish decline, can you talk us through how these have altered the flow of the river?
Sandy Galloway: Like many rivers, the Ems has been subject to significant anthropogenic events throughout its challenging history, and today we are seeing the cumulative impact of this. To explain it we need to understand how the river has changed over time from its source.
Human management of the river goes back many centuries, with mills and fisheries recorded around Westbourne from the medieval period. These were practical uses of the river: flowing water provided power for grinding grain and supported fishing. In later centuries the Ems was engineered for agriculture, particularly through water meadows, where channels, carriers and drains were created to move water across the land and improve grass and fodder production. The clean chalk water was also diverted through watercress beds.
By the 18th century, milling had become increasingly connected with the development of Emsworth, with Lumley Mill and Slipper Mill supplying goods towards Portsmouth and the navy. Each of these activities required water to be diverted, impounded or controlled through leats, weirs, sluices and other structures.
During the 19th and 20th centuries, the water demand increased as piped public supplies developed and groundwater abstraction from the chalk aquifer became increasingly important. Significant modern abstraction affecting the Ems appears to date particularly from the 1960s onwards. This matters because the Ems is groundwater-fed: reducing groundwater levels can reduce the amount of water emerging through its springs and can cause the point at which the river begins flowing to move downstream. Later infrastructure added another layer of alteration – the 1988 A27 Emsworth bypass required the river system to be engineered around major transport infrastructure.
By September 2020, severe low flows and drying had become a highly visible local issue and Friends of the Ems emerged around this period. The Environment Agency has subsequently identified abstraction management as an important factor affecting the Ems, while Portsmouth Water has undertaken hydrological investigations and become involved in a restoration programme.
The river flows from springs on the coastal side of the South Downs. These springs discharge at varying points within the catchment depending on the groundwater levels.
North of Westbourne village the river was previously diverted west, later to be modified as a water meadow, with the typical bedworks, carrier channels and drains. This activity destroyed much of the natural river structure.
The diversion also brought the main river and a significant tributary (the Aldsworth Stream) together into a canal-like reservoir providing a water supply to the nearby property and a water mill. With this came various sills, sluices and one of two mill leats. One of these serves as a carrier channel for another area of water meadows below Westbourne. On the south side the demolished mill site has a sluice controlling flow and a failed inverted siphon (a type of culvert used to direct water under infrastructure using gravity and internal pressure) to transport water under the A27. In effect, creating a totally blocked waterway!
At the bottom of the catchment, the river is further divided. One limb flows into a tidal mill pond where the converted redundant mill remains. The mill pond has remaining tidal gates that are now only open at a few spring tides for de-silting purposes – a rare opportunity for a few migratory fish to enter the river despite low flows and the many barriers that stand in their way, including two significant penstocks (a closed pipe or sluice gate used to control, direct or stop the flow of water).
The second limb of the lower river flows through a canalised waterway and a moderate weir, maintaining the water level within the property and gardens through which it flows. It runs under an old, redundant corn mill with a large grill to stop tidal debris from obstructing existing river flow.
WildFish: Water abstraction is another significant concern on the River Ems, and in September 2020 the middle reaches ran dry. Tell us how this worrying advancement in environmental decline sparked local action?
Sandy Galloway: Until that point there had been surprisingly little public concern about the river, other than a tacit acceptance of drying in the upper reaches and significantly reduced flows during summer months.
The events of 2020 were a catalyst for the formation of the Friends of the Ems – at the time, we knew little about the history of the river and even less about the complexities of the hydrology. Fast forward several years later, and we are now well-versed in the complex and challenging history of the Ems.
Over-abstraction is an area of continued concern for the group, particularly Portsmouth Water’s dependence on the river to meet public supply.
The continued drive to source more water from the river underpins the increased abstraction from the aquifer, leading to reduced flows and the likely development of the ‘new layer’ of obstruction to a healthy river habitat.
The current abstraction licence expires at the end of March 2028. It is essential that the Environment Agency secures a sustainable abstraction regime following the scheduled licence review and even then it may be too late to prevent irreversible decline. Based on the ability of the local aquifer to recharge there would need to be a 75% reduction in abstraction, and to achieve a high environmental ambition as defined by the Environment Agency the reduction would need to be 100%.
If you want to be a Friend of the River Ems and its streams, you can get involved by signing up as a supporter. To sign up, email greeningwestbourne@hotmail.co.uk and mention you’d like to join FOTE.
Meanwhile, WildFish will continue to campaign – and when necessary, take legal action – to help fight against companies that over-abstract from rivers. Estimates show nearly a quarter of English rivers are at serious risk from unsustainable water abstraction. Find out more via the WildFish website.
CLICK HERE TO DONATE TO OUR CROWDFUNDER
HELP US BECOME STRONGER SO THAT WE CAN CONTINUE TO DELIVER POWERFUL CITIZEN JOURNALISM!
