Thanks to the determination of volunteers the 10 kilometres stretch between Byrons Pool and Jesus Green lock is now clear of floating pennywort.

The invasive non-native aquatic plant had formed thick mats along the river and was growing at a rate of 20 centimetre a day. This meant back channels were lost, navigation for boaters and canoers was difficult and repercussions for wildlife and plants was more likely.

The Environment Agency and the Cam Conservators undertook the initial surveys and worked together to remove large masses of the invasive plant with weed boats.

The Floating Pennywort on the river Cam before the volunteers removed it.

The Floating Pennywort on the river Cam before the volunteers helped to remove it.

Mike Foley, a retired volunteer at Cam Valley Forum, continued the work and has spent years tackling the invasion on the River Cam. Mike has worked relentlessly to clear the invasive plant. Over the last year he worked extra hard to ensure the momentum carried on when meeting in groups has been difficult to coordinate.

Anne Miller, a volunteer who worked closely with Mike, helped raise funds so they were able to prune 3 kilometres of overhanging branches. This allowed them to remove pennywort which was trapped, this was critical in the elimination of the invasive plant.

The same stretch of the river Cam as above but with the Floating Pennywort removed.

The same stretch of the river Cam as above but with the Floating Pennywort removed.

Anne Miller, a volunteer from the Cam Valley Forum, said:

I was saddened to see the river above Cambridge getting clogged with this invasive weed and was inspired by Mike to start tackling it. There was hundreds of tonnes of material to remove and the pennywort was tangled in tree branches, so I thought we needed help.

Thanks to funding from the Environment Agency and others, I engaged some contractors who did a brilliant job in removing drooping tree branches on a 3 kilometre stretch above Cambridge. This sort of partnership working is very satisfying.

Mike Foley, a volunteer from the Cam Valley Forum, said:

It is great to see this stretch of the River Cam free from pennywort. Once you start to remove this invasive plant it is impossible to stop as you just want to see the job done. I would like to thank everyone who got involved and helped us along the way. This project is evidence that hard work pays off and we are better working together.

James Brokenshire- Dyke, a project engineer at the Environment Agency, said:

Mike has gone above and beyond to clear the pennywort. He digs and handpicks the plant, he conducts numerous walks to check it hasn’t grown back, and talks with various people to raise awareness and so much more.

Without him the pennywort would have spread further and we would not be aware of new outbreaks. Mike’s work is invaluable to us, as is all the volunteers who have contributed.

Tom Larnach, river manager at Cam Conservators, said:

Working with Mike and the volunteers has been great, we are only a small team so we really appreciate all their help. This project has been a good example of partnership working. Normally this time of year we start to see pennywort mats forming but I haven’t seen 1 bit.

Mike Foley, a volunteer from Cam Valley Forum, standing on the riverbank.

Mike Foley, a volunteer from Cam Valley Forum, standing on the riverbank.

Pennywort can change the availability of oxygen in the water which threatens fish and invertebrates. It can also choke drainage systems and crowd native water plants.

Members of the public can stop the spread of this invasive species by recording any sightings on the iRecord App.

Boaters and other users can also help by following the Check, Clean and Dry procedures.

  • Check: Check your equipment and clothes for live organisms – in particular areas that are damp or hard to inspect.
  • Clean: Clean and wash all your equipment, footwear and clothes thoroughly. Use hot water if possible. If you find one of these organisms leave them at the water body where you found them.
  • Dry: Dry all equipment and clothing – some species can live for many days in moist conditions. Make sure you don’t transfer them somewhere else.

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    Volunteers clear floating pennywort from 10km of the River Cam

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