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Case study: Yorkshire

Last edited: Mar 22, 2022, 4:54 PM

The project has an ambitious goal to eliminate floating pennywort from the rivers and canals of Yorkshire, based on the following:

Find it
  • Find the upstream / downstream limits;
  • Understand where the main areas of infestation and ‘Hot-Spots’ are
Agree who should treat it
  • Environment Agency? Canal & River Trust? Landowner?
Kill it
  • Treat headwater down;
  • Use a range of treatments;
  • Ensure fragments are removed along with the large mats;
  • Repeat year after year.
Crimpsall Sluice is an EA asset on the River Don in central Doncaster. It is also a popular fishing spot with numerous pegs. Until 2018 floating pennywort gathered in dense stands at this ‘hot-spot’ and we received repeated complaints from the Doncaster & District Angling Group.

Repeated chemical treatments completely cleared it in 2018. Now floating pennywort is infrequent, occasionally snagging on the trees to the left. It is monitored regularly by the angling group and treated twice yearly if required.

Images: Environment Agency

The project

Brief history of infestation and how the project to remove it started. Why did people want to do the removal?
  • Floating pennywort was first reported in Yorkshire in 2011;
  • Pressure to treat it came from anglers, Rivers Trusts and impact to Environment Agency (EA) and Canal & River Trust (CRT) assets;
  • The Yorkshire Floating pennywort Forum was formed in 2012;
  • Between 2012 and 2015 rivers and canals were treated, but not some navigable rivers;
  • In 2016 and 2017 there was no EA treatment. A floating pennywort survey was undertaken of all rivers in 2017;
  • In December 2017 EA and CRT met to confirm who would treat what. For the first time all waterways would now be under treatment.
Waterbody name and type
  • Most floating pennywort in Yorkshire is on the rivers and canals of the Calder, Aire and Don & Rother catchments;
  • In these lowland areas of south and west Yorkshire there is a network of intertwined slow-flowing rivers (often navigable) and canals;
  • There is only one known location in the whole of north and east Yorkshire.
Specific area worked on
  • 80km of Yorkshire Rivers and canals are now under continuous yearly treatment.
What went well?
  • Having a Yorkshire Floating pennywort Forum;
  • The 2017 survey established good baseline data (but only included rivers);
  • The 2017 meetings with CRT to agree areas of responsibility were pivotal;
  • In 2018 we secured ongoing funding from the EA Flood Defence team which meant that treatment is now guaranteed for main rivers.
What did not go so well? Lessons learnt
  • The 2017 surveys should have included canals;
  • Until 2018 treatment was disjointed. There was confusion over who was responsible for navigable rivers;
  • Treatment methodologies between EA and CRT remain inconsistent;
  • Untreated ‘Hot-Spots’ occur around weirs, booms and rock-ramps;
  • EA should use volunteers where possible at key locations.

Applying chemical treatments to floating pennywort. Image: River Stewardship Company

Methods used? What was done on site and how?

Main rivers / navigable rivers (EA)
  • Since 2018 EA control has involved headwaters-down sweeps from a boat. Two full rounds of chemical treatment are applied using a long-arm lance. Roundup Pro-Biactive is used with an appropriate adjuvant (Topfilm or Codacile Oil);
  • Volunteers have only been used to date for reporting floating pennywort and attending floating pennywort Forum meetings.
Canals (CRT)
  • CRT use a mixture of treatments;
  • Mechanical treatment involves the use of a weed-cutting boat when stands become too large for chemical control. Amphibious ‘Truxors’ are often used which can be fitted with a variety of equipment such as weed cutters, dredging arm, scoops, etc.
  • CRT have used paddlers including affiliated BC clubs and individual paddlers on some canals such as the Aire and Calder Navigation at Stanley Ferry and the Dewsbury Arm of the Calder and Hebble in Dewsbury. Both exercises were extremely successful.
Who was involved
  • EA use River Stewardship Company (RSC) as contractors.
  • CRT use Fountains PLC as contractors.
Timeline

Main rivers / navigable rivers (EA)
  • Two rounds of treatment are applied in June and August.
Canals (CRT)
  • Treatment is undertaken throughout the growing year and is often reactive (responding to outbreaks rather than a routine maintenance operation).
Frequency

See above.

Resources available, including equipment used
  • EA and CRT now spend approximately £20K each per annum on treatment in Yorkshire.
Access and permissions
  • EA and CRT do not seek landowner permission and undertake work using their statutory powers. Both still need AqHerb01 consent.
Outcomes and what was achieved
  • Floating pennywort no longer present on River Rother. Since 2018 EA have reduced floating pennywort on other main rivers by 80%. CRT similar impact on canals. ‘Hot-Spots’ remain.
Any biosecurity measures put in place

Main rivers / navigable rivers (EA)
  • RSC utilise stringent biosecurity measures, using the Check-Clean-Dry principles as a standard. In addition:
  • They have a dedicated storage area for boats and equipment that allow them to be cleaned and thoroughly dried between operations;
  • They plan work to ensure that they never cross catchments before boats and equipment are thoroughly dried;
  • All staff undertaken annual NNSS Biosecurity training with competency certificate available on request;
  • 2x sets of new improved chemical coveralls per operative (multi use);
  • No site cross contamination with re-use of single use suits;
  • Further details on Check Clean Dry are detailed within the RSC documented procedure “Biosecurity Procedure”.
  • Regular site audits.

The future

  • It is hoped that a single contractor will be used in future for both canals and rivers. This would make for a more efficient and co-ordinated approach;
  • A network of volunteer groups should then be established who could focus on monitoring & treating ‘hot-spot’ areas.
  • Best Practice would be (where possible) to utilise volunteers to undertake pennywort patrols every 2 weeks to mop up any new growths of pennywort.
Any other comments
  • Floating pennywort also exists in offline ponds and lakes in Yorkshire and here the approach is to help landowners control it with appropriate guidance. If online EA may help financially to avoid risk of contaminating river systems;
  • Treatment can be difficult in ponds / lakes as the floating pennywort may be within stands of native vegetation. They may also be in protected areas (e.g. SSSI’s or Local Wildlife Sites) or they may contain protected species (e.g. great crested newts).
Contact lead for further information

Contact Andrew.virtue@environment-agency.gov.uk 07766 161720

Return to the main floating pennywort strategy page.