Case study:River Monnow (Going Native)

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Location: 51° 54' 41.03" N, 2° 56' 21.69" W

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Project overview

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Status	In progress
Project web site	http://www.monnow.org/
Themes	Fisheries, Habitat and biodiversity
Country	England, Wales
Main contact forename	nick
Main contact surname	elbourne
Main contact user ID	User:NickRRC
Contact organisation	River Restoration Centre
Contact organisation web site
Partner organisations
Parent multi-site project
This is a parent project encompassing the following projects	No

River Monnow after invasive non-native species removal

Project summary

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The River catchment was dominated by invasive non-native species, specifically American mink and Himalayan Balsam, as well as Japanese Knotweed and Giant Hogweed. Their presence in the catchment was having a significant effect not only on ecology, but also access for recreational activities such as walking and fishing. Project objectives included:

• The identification of bankside areas affected by invasive non-native species

• Achieve catchment wide eradication of Himalayan Balsam (HB), Japanese Knotweed (JK) and Giant Hogweed (GHW)

• Maintain mink free status of the catchment (developed by the game and wildlife conservation trust) to monitor and control mink and reintroduce water voles to the River Dore

• Educate children, local community and other catchments about invasive non-native species and the River Monnow project

All sites with GHW and JK were mapped in 2007, as well as an estimation of the upper extent of HB sites on tributaries. Volunteers were used to spray and hand pulled large areas of HB which was repeated 3 or 4 times before the first frost. All HB sites were revisited several times to ensure no plants went to seed, and the control area was extended, again with the use of volunteers. After year 3 of treatments HB had been eradicated. This process of HB eradication was rolled out catchment wide using paid contractors, with follow up by volunteers. By Autumn 2012 70km of previously effected area will have had the initial treatment phase, with 25km of the catchment now HB free. GNW and JK was sprayed in the spring and treated in the autumn annually, however these were not widespread in the catchment. Costs for the last three years of work amount to £60,000 with 4,600 paid-for man hours and 1,200 voluntary hours. This equates to a figure so far of £822 per kilometre with an effort of 87 man hours per kilometre. Two more years of work are estimated (mainly hand-pulling and largely by volunteers), which would add a further 20% to those figures. The project has been funded by Environment Agency, Natural England and Tidy Towns Wales. Generous private donations from fishery owners and fund-raising by the association has added to the project budget. Mink have been monitored by volunteers, with captured numbers reducing to just 5 in 2007. Volunteers also annually monitor areas where water voles have been reintroduced, numbers and range are increasing. Two schools have been introduced to “the joys of Mayfly in the classroom”, to introduce children to the importance of healthy rivers and the connection between fishing and conservation. Produced and erected 100 signs on footpaths identifying the problem of HB. By 2014 the project aims to have eradicated HB from the catchment. Natural bankside vegetation is already re-established in many areas, significantly reducing erosion and sediment release.

Monitoring surveys and results

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Lessons learnt

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Catchment and subcatchment

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Subcatchment:Monnow

Site

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Name	River Monnow, Herefordshire and Monmouthshire
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body	No
National/international site designation
Local/regional site designations	water vole (habitat for protectes species)
Protected species present	Yes
Invasive species present	Yes
Species of interest	invasive non-native species: American mink, Himalayan Balsam, Japanese Knotweed, Giant Hogweed
Dominant hydrology
Dominant substrate
River corridor land use
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m³/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m²)

Project background

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Reach length directly affected (m)	25,00025,000 m <br />25 km <br />2,500,000 cm <br />
Project started	2007
Works started
Works completed
Project completed	2014/01/01
Total cost category	50 - 100 k€
Total cost (k€)
Benefit to cost ratio
Funding sources	Environment Agency, Natural England, Tidy Towns Wales, Monnow Rivers Association fundraising, private donations

Cost for project phases

Supplementary funding information

Costs for the last three years of work (2010 to 2013) amount to £60,000 with 4,600 paid-for man hours and 1,200 voluntary hours. This equates to a figure so far of £822 per kilometre with an effort of 87 man hours per kilometre. Two more years of work are estimated (mainly hand-pulling and largely by volunteers), which would add a further 20% to those figures.

Reasons for river restoration

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Mitigation of a pressure	invasive non-native species
Hydromorphology
Biology
Physico-chemical
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Measures

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Structural measures
Bank/bed modifications	removal of invasive non-native species (bankside vegetation)
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)	Two schools have been introduced to “the joys of Mayfly in the classroom”, and erected 100 signs on footpaths identifying the problem of Himalayan Balsam
Other