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Colne Community

The River Colne – eighteenth century to the present day

The River Colne played an important role to local communities and contributed significantly to local industries such as water mills since the eighteenth century. Mills were an important local industry at the end of the eighteenth century and there were thirteen in the Uxbridge area alone which were used by local farms.

“Mills on the River Colne are getting few and far between, and whereas a couple of thousand years ago there were scores of Colne Mills gaily going round and busily at work, there are, at present day, barely two dozen, and, alas! Even some of these are silent or even derelict”.

S. Springall (1907)

Other settlements within the area began to develop and grow, such as Colnbrook in the Nineteenth century as a river crossing and staging post. In general, the area prospered due to developments in transport, which in turn stimulated new industries and phases of house building. One such development was the construction of the Grand Union Canal. During the industrial revolution there was a great demand for improvements in transportation, especially between the industrialised Midlands and London. A canal route through Harrow was rejected in favour of the less popular plan to follow the Colne Valley. The canal stimulated local industries, such as copper works and sand and gravel extractions.

Colne Valley Park: A brief History (2003)

Wild Trout Trust river workshops

Colne wild trout river workshop

Wild Trout river workshop (courtesy of the Environment Agency, 2014).

In spring each year, workshops are run by the Wild Trout Trust which provides an excellent opportunity for us to work in partnership with the Environment Agency, Chiltern Chalk Streams Project and Hertfordshire County Council.


The aim of the workshops was to teach the use of tools and techniques for habitat improvement and management in order to enhance the rivers in our supply regions.

Our involvement

Workshops included installing a number of in-stream features to improve the habitat for fish and other wildlife. Mid-stream flow deflectors were installed to provide additional habitat for fish through the creation of scour pools and areas of slack water. Cover boards were secured to the riverbed to provide refuge areas for fish and river shelves were created by securing fallen trees to the bed and bank of the river. The shelves not only created additional habitat for wildlife, but also reduced the likelihood of flooding. All interest groups involved are now using these tools and techniques in order to protect the rivers and habitats in Hertfordshire.

Find out more about the Wild Trout Trust river workshops

Tree management at Springwell Lake


A crane was needed to lift the felled poplars at Springwell Lake


We recently completed a large scale tree management project on our site Springwell Lake, near Rickmansworth. The project looked to enhance the health of the trees there and to allow them to continue to grow, which would help with their future management. The work also included liaising with the Environment Agency in order to preserve the various habitats around the work area, including birds and water voles.

Our involvement

This large scale project involved detailed planning and required the closure of the footpath around the lake. Over a four week period, four diseased hybrid poplar trees measuring 30 metres in height had to be safely felled. A 130 tonne crane then lifted them from the lake shore over the River Colne back stream and onto neighbouring land, where the wood was processed and removed from the site. Tree teams worked around the clock to pollard and dead wood a large number of trees at the site allowing the remaining trees to grow healthily. With regards to the various habitats in the area, the team used wood from the tree work to construct eco piles, which will provide a habitat for a range of species. The works also allowed more light into the river channel which will benefit aquatic plants, providing new habitats for aquatic species.

We are also are currently working in partnership with Herts and Middlesex Wildlife Trust (HMWT) on the Springwell Lake reed bed restoration project. Reed beds are among one of the most important habitats for breeding birds in the UK and support a number of species, including the nationally rare Bittern.

Hilfield Park Reservoir, Hertfordshire

Hilfield Park Reservoir was constructed in 1955 by the Colne Valley Water Company, a predecessor of Affinity Water. It was built across a natural valley and formed by a concrete and earth dam. Since 1969, it has been a local nature reserve managed by HMWT on our behalf for wildlife conservation.

The site, not currently used for operational purposes, can be accessed by arrangement with HMWT. Public access has been restricted so the diverse habitats have the opportunity to flourish undisturbed. The site is of high ecological importance in the region due to the water birds it supports throughout the year.

In addition to flocks of Moulting Duck in late summer and significant populations of several waterfowl species in winter, the breeding birds are of particular importance. The Black-necked Grebe is a species of national significance. The reservoir supports other habitats, including that of the water vole and good butterfly and dragonfly assemblages. We are working with HMWT to maximise the potential of the site and to help protect key species.

 Hillfield park reservoir

View from Hilfield Park Reservoir

Zero Metaldehyde pilot project in the Mimmshall Brook


Metaldehyde is the active ingredient contained within slug pellets that are used by UK farmers to control slugs while growing a variety of crop types. Levels of metaldehyde have been detected within surface water systems since measurements of this substance began in 2008.


Whilst the metaldehyde levels detected pose no danger to human health or the environment, breaching the EU Drinking Water Limit of 0.1μg/l must be avoided and water companies must aim to meet their obligations under the Drinking Water Inspectorate (DWI). The aim of this project is to: ‘Develop a consistent and acceptable process of identifying specific geographical locations at which to target specific measures to reduce the metaldehyde input in water catchments’.

Our Investigation

To investigate ways to reduce diffuse metaldehyde pollution at the source, we have established a Zero Metaldehyde pilot project with the Metaldehyde Stewardship Group, Natural England’s Catchment Sensitive Farming initiative and a number of other water companies to help with this project.

Our Involvement

The Mimmshall Brook catchment close to Potters Bar and Borehamwood in Hertfordshire was chosen for the pilot, along with three other catchments nationally. A standard set of high-risk field maps were produced for individual fields, based on the three key elements of soil run-off/leaching potential, field slope and proximity to a watercourse.

The high-risk field map showed the high-risk fields in the catchment and farmers in these areas are being asked to voluntarily use an alternative to metaldehyde on these fields. The pilot commenced in 2014 and will run until 2016. For more information please visit

ColneCAN Partnership

The Colne Catchment Action Network Partnership (ColneCAN) was established in 2011 and is hosted by the Chilterns Chalk Stream and Thames Valley Groundwork’s. The ColneCAN ties together the work of the Colne Valley Regional Park and the Chilterns Chalk Stream Project with the wider catchment. ColneCAN brings together water companies, local authorities, charities, anglers, conservationists, other stakeholders and local residents to ensure catchment-wide thinking and local action.

We are working closely with local environmental groups and, more recently, a number of catchment partnerships in the Colne catchment. Our catchment management team regularly monitors the River Colne and its tributaries for untreated water quality and undertakes a wide range of surveys and activities, to help us understand the potential impacts of pollution on our water abstractions.

River Monitoring

Our Catchment Team undertakes routine river water quality monitoring at strategic sites along the rivers in the Colne catchment to help us understand the source and pathways of pollution which could enter our water abstraction.

Catchment Risk Assessments and Land Use Surveys

Our Catchment Team undertakes risk assessments for each source of abstraction using Environment Agency groundwater source protection zones to identify surrounding land uses (such as industrial, residential and agricultural), their associated pollutants and the potential impact to our abstractions and treatment processes. This helps us to understand the local catchment, the source and pathway for potential pollutants, as well as any potential impacts on our abstractions.

Partnership working

Our Catchment Team works closely with a wide range of partners, from neighbouring water companies, the Environment Agency, Natural England and local environment groups to identify ways to improve water quality. We strongly support and work alongside the Colne Can Catchment Partnership.

In addition, we also support water industry research to further enhance the way in which we manage risks, through better technology at the source, in the catchment and at our treatment works.

Colne Valley Park and Community Interest Company

Affinity Water is proud to be a Corporate Supporter of the Colne Valley Park Community Interest Company (CIC). The Colne Valley Regional Park covers 111 square km from Rickmansworth in the north to Staines in the south, Uxbridge and Heathrow in the east to Chalfont and Slough in the west. It is the first piece of countryside to the west of London and includes over 70 lakes, 200km of rivers and canals, eight country Parks and other visitor access hubs, 19 nature reserves, 13 SSSI’s and a 270km network of footpaths and bridleways connecting it all together. Our landholdings stretch throughout the Regional Park from Stockers Lake to Wraysbury Lakes and we are keen to support the CIC to help achieve its core objectives. These include:

  • To maintain and enhance the landscape, historic environment and waterscape of the Park in terms of its scenic and conservation value and its overall amenity
  • To safeguard the countryside of the Park from inappropriate development. Where development is permissible, it will encourage the highest possible standards of design
  • To conserve and enhance biodiversity within the Park through the protection and management of its species, habitats and geological features
  • To provide opportunities for countryside recreation and ensure that facilities are accessible to all
  • To achieve a vibrant and sustainable rural economy, including farming and forestry, underpinning the value of the countryside
  • To encourage community participation, including volunteering and environmental education
  • To promote the health and social well-being benefits that access to high quality green space brings

For more information, please visit:

Colne partnership

Affinity Water staff being recognised as being founding supporters of the Colne Valley Park CIC.

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