Invasive Species Eradication Project 2021-2025

Invasive non-native species are one of the largest global threats to biodiversity. Our award-winning Canal & River Invasive Species Eradication Project is working to eradicate them from our waterways.

In between Dudley and Stourbridge, a battle is underway removing an invasive plant that is choking our waterways. This sort of species of weed is very knotty and sticks together, but it’s one of the harder ones to get out. This is floating pennywort. So, floating pennywort originates from the Americas, predominantly South America. It was introduced into the UK around the 19th century. The big problem with floating pennywort is that it grows very rapidly. It can grow up to 20 centimetres a day. But also, it can clog waterways, it can impact native wildlife and cause issues for navigation as well on our canals. In a few weeks time, the team will return. If they miss even the smallest scrap of pennywort, the plant can quickly regrow and leave you back at square one, but that’s what’s different about this £600,000 project. It’s not just about controlling these four invasive species – giant hogweed, Japanese knotweed, floating pennywort, and water fern or Azolla – it’s about eradicating them completely, and to do that, you can physically pull out things like floating pennywort that’s what they’re doing here. Some of the other plants, you inject weed killer directly into their stems or destroy them with electricity and then for things like Azolla, you actually release a weevil that eats the plant and kills it that way. The work is funded by water company Severn Trent and it doesn’t just benefit boat owners and wildlife. Some species of invasive non-native species can cause water quality to decrease, so by removing some of these species, we can increase our water quality and that reduce the number of chemicals we use at our treatment plants and that reduces our operating costs, then in turn that can help reduce our customer bills. Right across the Midlands, war has been declared on these plant pests. David Gregory Kumar, BBC Midlands Today, Brierley Hill.

Our team are working on a ground-breaking new project to eradicate four priority invasive plant species that have found their way into our waterways.

These are Japanese knotweed, giant hogweed, floating pennywort and water fern (Azolla).

The problem

These four plant species, which have accidentally been introduced into our canals and rivers from other parts of the world, can cause major damage by:

Out-competing native wildlife and impacting other species critical to native biodiversity
Damaging eco-systems and their functionality
Posing a public and ecological health risk by spreading diseases and producing dangerous substances
Blocking canals by forming thick green carpets on the water. This also impedes navigation, clogs up propellers and damages boats
Increasing the potential risk of flooding
Impacting water quality for native fish and aquatic plants
Damaging infrastructure including canal banks and earth structures

With the likes of floating pennywort growing as much as 20cm a day, the race is on to prevent major and irreversible damage.

Before and after: eradicating invasive aquatic species

Witness the transformation and discover how much floating pennywort and water fern we are extracting from our waterways

The project

We are tackling these invasive species in innovative, first-of-their-kind ways. With funding from Severn Trent's Great Big Nature Boost Scheme, we have now launched Canal & River Invasive Species Eradication Project, a four-year project in the Severn Trent supply area.

This £600,000 project is the largest invasive species eradication project on UK inland waterways. It covers a significant geographical area, spanning several of our regions and the entirety of the Midlands across Severn Trent's supply area.

We are delighted to have won the NGO Impact Award 2022 award from the Chartered Institute of Ecology & Environmental Management (CIEEM) for this project. This award recognises the achievement of NGOs in delivering an initiative that has had a major impact in benefitting nature and society.

The impact

In just one year of the four-year project, we have successfully treated a total of 200km of waterway. This includes:

Targeted treatment in over 300 land-based invasive species sites
Mechanical removal of floating pennywort in five of our West Midlands waterways, spanning across 11km of canal
Biocontrolled release of Azolla weevils across 10km of waterways in the West Midlands

South American weevils being released onto floating pennywort

Using weevils to fight floating pennywort

In a first-of-its-kind trial, we've released South American weevils into the River Soar to help eradicate floating pennywort

Eradicating Himalayan balsam in new ways

Using only natural materials, we're monitoring a trial site at the Penarth Feeder to see whether this innovative method will be successful in the fight against Himalayan balsam

Removing floating pennywort using a weed conver boat

Removing 7km of floating pennywort

Using weed conver boats, we cleared over 250 tonnes of floating pennywort on the River Soar in five weeks

The team will be keeping a close eye on the presence of invasive species in their designated areas and how the project is making a positive impact to our blue and green spaces.

This regular monitoring will allow us to move forward in the most effective way as we continue to battle invasive species.

How you can join the fight against INNS

If you spend time on our canals and rivers, one of the most important things you can do is to remember to Check, Clean, Dry. These steps help stop the spread of harmful plants and animals to a new area, and should always be done before exiting a waterway - even if you are moving to another spot just a few miles away.

If you would like to volunteer on this project with us, we are currently looking for someone to help out with admin and reporting. Please contact Charles Hughes for more information.

We will also be looking for more volunteers to help manage some of the sites we are working on. Check back here for further details soon.

Want to learn more?

Find out more about invasive species, our work to eradicate them and other volunteering opportunities

Last Edited: 22 December 2023

Invasive Species Eradication Project 2021-2025

The problem

The project

The impact

How you can join the fight against INNS

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