River Colne Catchment Action Network

Catchment projects

Hover over a numbered spot to see a project summary. Click on a spot to see the full project details. Alternatively view the project list.

The Colne rises from a subterranean river at a spring in North Mymms Park. Tributaries of the Colne include the Mimmshall Brook, Tykes Water, River Ver and Ellen Brook.

13. Micropollutants Study

Aims: Improve water quality

Project to identify the micropollutants present in surface, groundwater and sediment samples along the River Colne and Ver from Lairage Land upstream to the source of the River Colne.

For more information refer to these news items here:

The River Colne, A Toxic Soup of Chemicals?

Analysis finds 267 micropollutants in the River Colne

The report itself:

Micro-pollutants in the River Colne: Colne Valley Fisheries Consultative, April 2023

12. Rediscovering the River Colne

Aim: Control invasive non-native species; Involve people with their local waterbodies; Improve wildlife corridors; Improve water quality; Manage flow; Work together

Rediscovering the River Colne is a ground breaking project that aspires to bring the River Colne to the heart of Watford Town and its people.

11. Farming 4 Clean Water

Aim: Involve people with their local waterbodies; Improve wildlife corridors; Improve water quality; Work together

Affinity Water is working local farmers and agronomists to reduce concentrations of metaldehyde (active ingredient in slug pellets) through a Payment for Ecosystems Services scheme.

10. Invasive non-native plant control strategy

Aim: Involve people with their local waterbodies; Work together

Strategy to control or erradicate non-native invasive plant species from the Upper Colne.

9. Watford in the Water

Aim: Control invasive non-native species; Involve people with their local waterbodies; Work together

‘Watford in the Water’ is a river Colne spring clean, health check and deep clean project.

8. Recording pollution incidents

Aims: Improve water quality

The Colne Valley Fisheries Consultative (CVFC) are leading on a pollution monitoring initiative.

The organisation have been recording outfall locations across the Colne catchment and have developed an app for recording pollution incidents: https://cvfc.org.uk/pollution/pollution1.php

The CVFC app can also be used for:

Recording non-native invasive species (link)
Retaining riverfly monitoring information (link)

7. Exploration into the removal of three river structures at Riverside Watford.

Aims: Improve water quality

Investigation into the possible removal of three river Colne structures.These comprise two sluice gates and a weir.

A section 106 legal agreement has been signed making the following commitment:

6. Japanese Knotweed Management Plan Watford Borough Council

Aims: Control invasive non-native species

Japanese Knotweed management plan treatment starting in March 2016 on Knutford Playing Fields, Riverside and other parts of Watford Borough Councils Land

5. Habitat Improvement River Colne Oxhey Park

Aims: Improve water quality

In order for the River Colne at Oxhey Park to better perform as a high quality habitat, a project is proposed to introduce a series of brushwood berms along the South bank and undertake some light maintenance works along the existing berms on the North Bank.

4. Upper Colne Riverfly Monitoring group

Aim: Involve people with their local waterbodies; Improve water quality; Work together

A riverfly group led by the Friends of Oxhey Park currently monitors three sites on the Colne in the Watford area. The group was set up through the Chilterns, Hertfordshire and Middlesex Riverfly Hub and began monitoring in November 2014.

3. Litter Boom at Oxhey Park

Aims: Improve wildlife corridors

The installation of litter boom on the Colne in Oxhey Park to trap rubbish, allowing clearance where the river enters the park.

2. Mimmshall Brook "Zero Metaldehyde" project

Aims: Improve water quality

Working with farmers in the Mimmshall Brook to reduce metaldehyde (pesticide in slug pellets) pollution impacting the river and drinking water abstraction

1. Improvements to access and wetlands at the Withey Beds

Aims: Involve people with their local waterbodies

A project to carry out some improvement works at the Withey Beds Local Nature Reserve, to include ditch management, creation of ponds and scrapes, provision of improved site interpretation, and extension of a board walk to provide access to the bird hide.