30. Invasive Non-Native Species Control

Theme: Habitats and wildlife


  • To maintain and enhance the river's natural habitats and wildlife

Project description

This project aims to eradicate invasive non-native species from the catchment.

Plants and animals that have been introduced into areas outside their natural range through human actions, and are posing a threat to native wildlife, are known as invasive non-native species (INNS).

There are several which are a particular problem within the Lea Catchment and people are working hard to control. The main issue tends to be that INNS outcompete or predate our native species and readily spread along the waterways colonising new areas and making them hard to fully eradicate.

Within the Lea Catchment (including all tributaries) there are four main non-native plants of concern:

  • Himalayan balsam - present on the all of the rivers.
  • Floating pennywort - present on the Stort and Lea.
  • Giant hogweed - present on the Stort, Lea, Beane, Rib
  • Japanese knotweed - present on the Stort and Lea (possibly others)
  • Other INNS present include yellow balsam, orange balsam and crassula.
    As well as plants, non-native American Mink are a big problem too and are the main cause of water vole declines across Herts and Middlesex in the last 50 years.

Various organisations, river groups, landowners and regulators are working hard to try to control and reduce the spread of INNS across the catchment. Each river partnership has its own approach to dealing with INNS and more help is needed to tackle this widespread problem.

Within the Stort it is being led by Whoosh Explore Canoe Club in partnership with Herts and Middlesex Wildlife Trust, Canal & Rivers Trust, Local Authorities, Environment Agency, landowners and conservation groups.

The project began in 2018 and a steering group was set up in 2020 to better coordinate INNS monitoring and control activities, making sure there is a joined up approach to tackling the problem. More information about the project can be found by following these links:

Project Pennywort

Riddance Not Control

Whoosh Explore Canoe Club are looking for sponsorship for the Himalayan Balsam Riddance Project, which would help them to buy dedicated canoes for undertaking the practical INNS work. 

If you would like to get involved or lead a project in your local area please get in touch.

Project lead: Whoosh Explore Canoe Club
Project partners: Environment Agency, Herts & Middlesex Wildlife Trust, Canal & River Trust, Local Authorities, landowners
Funding source: Affinity Community Grant (to kick start)
Project start: 2019
Project end: Ongoing
Contact for more information: This email address is being protected from spambots. You need JavaScript enabled to view it.

Design by LTD Design Consultants and build by Garganey Consulting.