Pennywort Status

For a detailed log of current pennywort status click here

The maps below show the status of pennywort on the Upper Cam at the year end (December).  Zoom into map and click on markers for more detail. See map key at the bottom of this page

(Note that this map doesn’t yet show floating pennywort below cambridge, although we  started to work on its eradication during 2019)


Further dramatic improvements on the upper river, thanks to vigilance by a number of volunteers on the bank and in canoes, who pick up the occasional fragments as they appear and hence stop them growing and spreading.  Floating Pennywort is now rare, although we will need to remain vigilent in 2020 at the hotspots of Grantchester Mill Pond, Swan Island ditch and downstream past Paradise Island and Paradise LNR to snobs stream.  There was a small patch in the privately owned wetlands opposite Red Lion Meadow. This has been removed but will need monitoring by authorised volunteers


Dramatic improvement in the pennywort situation, thanks to intensive work by contractor and volunteers during 2018. Small hotspots remain at Grantchester Mill Pond, Swan Island ditch and Snobs Stream, but otherwise there’s no visible pennywort at the year end.  We’ll need to remain vigilant in 2019 though, especially once the growing season starts, to make sure we haven’t missed any, and to complete the eradication in the hotspots



Chilling video of kayakers pushing through the pennywort at pinch point 2 on upper Cam on 4 Dec 2016

Map key:

Turquoise: Clear of floating pennywort at year end, but present during the year.
Orange: Occasional patches of floating pennywort.
Red: Frequent or continuous mats of floating pennywort.
Black markers: Completely covered by floating pennywort, at least once during the year.
Turquoise markers: Upper limit of floating pennywort.

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