Welcome to River of the Month! Every month, we spotlight a different river, sharing its wonders, its challenges, and the incredible people fighting to protect it. This month is…

The River Itchen

 

By Sue George and Paul Vignaux, Test & Itchen Association

 

The River Itchen weaves through the heart of Hampshire and is one of the world’s rare chalk streams. These rivers flow through chalk hills that act as natural filters, giving the water its famous crystal clarity. Rich in minerals and with cool, steadily flowing waters, chalk streams create unique ecosystems that support many rare species, some endangered. Delicate water crowfoot, wild brown trout, water voles, otters, southern damselfly, mayflies and the endangered white-clawed crawfish are found in its waters. Local people enjoy its many riverside walks in and around Arlesford, Winchester and the Itchen Navigation Canal from Winchester to Eastleigh. Globally famous for its fly-fishing heritage, it is one of the main 6 chalk rivers in England that create the conditions needed by the endangered Atlantic Salmon to spawn and grow before heading out to sea within the year.  The Itchen has been designated as a Site of Special Scientific Interest and Special Area of Conservation.

River Facts

 

Did you know?

1) There’s evidence that the River Itchen supported agricultural settlements from the Neolithic period (4000 BC to 2500 BC) when farming first began and throughout the Bronze and Iron Ages.

2) In Roman times, engineers diverted its flow to serve the growing city of Winchester.

3) Salmon have swum in its waters for tens of thousands of years.

Length:

42 km

Catchment area:

119 km²

County:

Hampshire

Fish Biodiversity:

High – home to wild brown trout and one of only 6 English chalk rivers supporting a unique chalk stream meta population of Atlantic salmon; essentially a sub species in its own right

Sewage Discharges in 2024:

351

Sewage Hours in 2024:

3,927 hours

Ecological Status:

The Environment Agency rates the main Itchen as Good although many of the headwaters are assessed as only Moderate. This year’s SSSI (SAC) condition assessment by Natural England has highlighted that the river is declining in many parts and rivers and streams are classified as ‘unfavourable no change’.

Chemical Status:

Fail. Recent research has revealed that the Itchen is polluted with residues from pesticides, household cleaning products, pharmaceuticals and personal care products, as well as industrial chemicals.  Waste water treatment generally doesn’t deal with these substances, in addition to PFAS, the ‘forever chemicals’ which don’t break down in the environment.

Overall Classification:

Moderate

The River Guardians

 

The Test & Itchen Association brings together river keepers, riparian owners, anglers, conservationists and local people to help protect and restore the River Itchen and its neighbouring chalk streams.

The Association has an established river monitoring network, with volunteers carrying out invertebrate sampling, associate smart rivers monitoring, and monthly Angling Trust WQMN pollution checks at dozens of sites. They also campaign for stronger action from water companies, government and local authorities, taking on polluters and bad planning proposals when needed.

The Association is only one of the partner organisations that make up the Test and Itchen catchment Partnership (TICP). The partners in the TICP work collaboratively with the Wessex Rivers Trust, the Watercress and Winterbournes Landscape Partnership Scheme, as well as Hampshire and Isle of Wight Wildlife Trust and many smaller community catchment partners who concentrate on specific tributaries or stretches.

The Friends of the Itchen Estuary have been doing some groundbreaking work on E coli monitoring. Last year, they carried out an intensive survey of Itchen Estuary E coli levels at 4 locations during the course of 2 x 12 hr tide cycles. Tests at a UKAS accredited lab showed that E coli levels at all locations would fail to meet EA minimum bathing water quality standards and were often extremely high. Citizen science and Southern Water data, obtained from Environmental Information Requests, revealed that the major source of sewage pollution is continuous effluent from Portswood Wastewater Treatment Works. Chemical and bacteriological water quality monitoring will resume this autumn. This year they will hold a series of public meetings to develop city-wide awareness of and engagement with the natural value of the Itchen Estuary – for ecology, wildlife, recreation, wellbeing and the local economy. This will support and contribute to a 2027 Southampton City Council sponsored River Charter.

In 2023, Wessex Rivers Trust restored a 380-metre stretch of the Itchen Navigation at Brambridge – an important salmon spawning area identified by the Environment Agency. Funded by the Test & Itchen Catchment Partnership’s Drought Resilience Fund, the Trust used locally sourced timber and brush to narrow the channel whilst introducing complexity and creating diverse habitats for salmon and other wildlife. The Trust has a pipeline of future projects for the River Itchen that will deliver significant habitat, fish passage, and water quality benefits to support a thriving aquatic ecosystem.

Hampshire and Isle of Wight Wildlife Trust’s work includes restoring vital floodplain wetlands, chalk stream habitats and key sections of the River Itchen, enhancing natural processes, reconnecting fragmented habitats, and tackling issues like over-abstraction and pollution that directly affect salmon populations. As part of the Save our Chalk Streams campaign, the Trust is also working with local authorities to raise “Rights of the River” motions. Through the river rights framework, the Trust aims to strengthen protections for chalk streams.

The Test and Itchen Invasive Non Native Species (INNS) Project is an ambitious multi-year partnership project aiming to reduce the impact of invasive non native species on the precious native wildlife and habitats of the Test and Itchen river catchments. The T&I INNS Project aims to bring together and maximise the efforts of community groups, fisheries, land managers, and local businesses to tackle the growing threat posed by invasive species on the integrity of these globally rare chalk streams.An exciting new development is the formation of Project White Hart – a growing coalition of local and national organisations with the ambitious vision to return the chalkstream salmon to abundance by 2050 in the Itchen, and the neighbouring River Test. 

Key Challenges

 

The River Itchen faces is under threat despite its status as a protected chalk stream and Special Area of Conservation. Chalk streams require a stable, cool flow of clean water to maintain their fragile ecosystems, so small changes in river conditions can have devastating effects. They are highly sensitive to over-abstraction, pollution and changes in water quality or temperature.

The steady flows and cool water that provide the conditions that many rare species need are now under threat from over-abstraction and climate change, particularly in the summer when flows are lowest. Large volumes of water are taken to satisfy public, agricultural and business demand for water. The Itchen’s catchment has been earmarked for high levels of housing development, which will severely increase this pressure. Prolonged dry periods and climate change make the river more vulnerable to drought, reducing its ability to dilute pollutants and sustain wildlife. Furthermore, the River Itchen faces additional challenges include:

• Microplastics. A new study by citizen scientists from the Upper Itchen Restoration CIC and University of Brighton has found the river’s headwaters are contaminated by microfibres, particles of plastic and fibreglass, raising urgent questions about the river’s health.
• Diffuse Pollution is a major threat, with the river vulnerable to contamination from household chemicals, pharmaceuticals and personal care products ending up in the river. A University of Portsmouth study found 121 polar-organic compounds in the river, 61 of which came from household use. Agricultural activity adds pollutants, nutrients and fine sediments that smother spawning gravels. The catchment includes major transport infrastructure, including Southampton airport, with highway drainage carrying oil, rubber and heavy metals into the river, adding another source of pollution.
• Sewage Pollution from storm overflows discharging untreated sewage on the lower reaches of the Itchen. In rural areas, many hundreds of households and businesses have off-mains drainage and poorly maintained septic tanks and small sewage discharges are a source of diffuse pollution.  Where smaller communities are served by waste water treatment, investment may be lacking for treatment options such as Phosphate stripping.  The drive to accelerate house building may outstrip the capacity of existing infrastructure (waste and clean water) to cope.
• Invasive non-native species such as Himalayan balsam and signal crayfish threaten native wildlife and habitats.

Key Solutions

 

1. Legal Protections for Chalk Streams – Define chalk streams as “irreplaceable habitats” which need enhanced legal protection. Strengthen planning policy to prevent developments that are not water neutral in their catchments.
2. Fast track new infrastructure projects – A new reservoir and water recycling and transfer project would reduce pressure on the Itchen, but these are not expected to be operational until at least 2032 and 2034 respectively. Already delayed several times, these projects must be prioritised and accelerated.
3. Upgrading or relocation of wastewater treatment plants that have been shown to be impacting on salmon migration and spawning.
4. Urgent action to reduce abstraction – Until new sources come online, Southern Water must intensify action to cut water use — including tightening rules on non-essential commercial water use during droughts.
5. Incentivise water saving – Until there are alternative sources of water, the Itchen will continue to be over-abstracted unless demand is reduced. We need incentives and awareness campaigns to convince the public and businesses to save water.
6. Reduce use of harmful household chemicals – new research has identified this as a bigger problem than previously thought. Urgent work is needed to reduce their use by households.
7. Upgrade and maintain off-mains drainage systems – make owners more aware of their impact on the river and the need to make sure that their systems are fit for purpose as per EA regulations and that they are maintained regularly.
8. Support regenerative farming – More support for farmers to adopt regenerative practices that reduce runoff, improve soil health, and prevent agricultural pollution from entering the river.
9. Invest in nature-based solutions – Investment in natural solutions such as river and wetland restoration, riparian buffer zones, barrier removal in the river and sustainable drainage systems in urban areas (SuDS)
10. Prepare for Climate Change – Climate change must be factored into every land and water management decision. Support tree planting, wetland creation, and restoration projects that enhance the Itchen’s resilience and remove barriers currently slowing them down.
11. Monitoring existing and emerging threats – Chalk streams are highly sensitive to changes in river conditions. Stronger and more frequent biological and chemical monitoring is essential for early detection of pollution, invasive species, and chemical threats.

If you would like to support those working to protect this rare chalk stream you can find out more here:

• Test & Itchen Catchment Partnership
• Test and Itchen Association
• Wessex Rivers Trust
• Hampshire & IoW Wildlife Trust 
• Upper Itchen Restoration CIC
• Friends of the Itchen Estuary
• Activist Anglers – Angling Trust

If you found this inspiring and would like to find out how you can protect your own local river by joining or creating your own river community group, visit our River Rescue Kit.