Case study:Pearls in Peril LIFE+ GB Project - River South Esk

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Location: 56° 52' 0", -3° 10' 24"
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Project overview

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Status Complete
Project web site
Themes Fisheries, Habitat and biodiversity, Hydromorphology, Water quality
Country Scotland
Main contact forename Jackie
Main contact surname Webley
Main contact user ID User:Pearlsinperil
Contact organisation Scottish Natural Heritage
Contact organisation web site
Partner organisations Esk District Salmon Fishery Board, SEPA
Parent multi-site project

Case_study:Pearls in Peril LIFE project

This is a parent project
encompassing the following
Pearls in Peril logo

Project summary

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The River South Esk is designated as a Special Area of Conservation with internationally important populations of freshwater pearl mussel and Atlantic salmon. It is presently assessed as being in ‘unfavourable’ condition by Scottish Natural Heritage (SNH). ‘Pearls in Peril’ is a UK-wide project to safeguard the future of the freshwater pearl mussel. The project undertook to restore sections of the River South Esk and an important tributary the 'White Water'. A study was commissioned to assess the impact of identified bank protection works on natural river processes and habitats important to the freshwater pearl mussel, prioritise sites for restoration and provide restoration designs.

A total of 21 bank protection sites in the upper river have previously been identified as impacting natural river processes since their construction during the 1990s. These are similar in appearance and purpose, comprising of large rock armour located on meander bends. They are present along three reaches of the upper River South Esk catchment, with nine at Moulzie in upper Glen Clova, eight at Acharn on the White Water upstream the confluence with the River South Esk, and four at Braedownie downstream of Acharn. There are no recorded populations of freshwater pearl mussel in these three river reaches, however downstream populations are influenced by the supply of suitable sediment from these reaches and by the health of the salmonid population.

Following stakeholder engagement,achieving all relevant licences and implementing necessary environmental protection measures; PIP removed 13 sections of rock armour river bank protection followed by bank reprofiling at Moulzie, Acharn and Braedownie as well as the re-connection of three paleochannels - one at Moulzie and two at Acharn on the main stem River South Esk and its tributary the White Water extending to 873m of in-stream river restoration work.

RIVER SOUTH ESK SPECIFIC PROJECT ACTIONS - Facilitate and implement improved riparian habitat in the River South Esk - work with land managers to develop SRDP riparian planting schemes on the River South Esk. - Implement in-stream restoration works in the River Dee and South Esk - Both the Dee and the South Esk are large rivers with a long history of human intervention and management. This has led to degraded in-steam habitat which is adversely affecting both pearl mussels and salmonids. For example, weirs and rock bank protection can interfere with sediment transport or supply processes and reduce the area of available pearl mussel habitat. Within the River Dee, work at eight priority sites will be delivered in this project, and six priority sites will be tackled on the South Esk. Work will include developing detailed design plans, managing contractors to deliver the work and pre and post monitoring of the sites to assess their impact. - Reduce nutrient and sediment input from diffuse pollution sources in the River Dee and South Esk - The River Dee and the South Esk have been identified as priority catchments for tackling diffuse pollution. Work with land-managers will aim to promote changes in land management activities which can reduce diffuse pollution. For example, encouraging land managers to create un-cropped and un-grazed riparian buffer strips. Where relevant, other diffuse pollution reduction activities will be promoted, such as constructed farm wetlands to filter run-off from steadings and alternative stock-watering systems. This will be delivered through SRDP schemes.

Monitoring surveys and results

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Riparian enhancement - 30,365 tress planted along the riparian zone of the river.

In stream restoration - The work was completed in August 2015. Monitoring work is now underway and being implemented by the Esk District Salmon Fishery Board. Following large floods in December 2015 initial observations are showing a wider channel, improved composition of river substrates, availability of new salmonid spawning habitat, channel has become more sinuous.

Reduce nutrient and sediment input from diffuse pollution - 22 land managers were engaged, awareness raising workshop was held, and >20km of water margin fencing was facilitated across the target area.

Lessons learnt

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The timescales involved from conception to completion were longer than anticipated. The site presents a range of environmental sensitivities and land uses that required further consideration as part of the planning and physical works processes.

Image gallery

75106 PIP South Esk 29 June 2016.jpg

Catchment and subcatchment


Name River South Esk
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
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use
Average bankfull channel width category
Average bankfull channel width (m)
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Average bankfull channel depth (m)
Mean discharge category
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Average unit stream power (W/m2)

Project background

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Works completed
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Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance

Reasons for river restoration

Mitigation of a pressure
Hydromorphology Channel pattern/planform
Other reasons for the project


Structural measures
Bank/bed modifications Bank improvement, Bank reprofiling
Floodplain / River corridor Riparian planting
Planform / Channel pattern
Non-structural measures
Management interventions Land management
Social measures (incl. engagement) Engagement with a wide range of stakeholders


Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

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Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Monitoring documents

Additional documents and videos

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Link Description

Supplementary Information

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In addition to in-stream restoration, Pearls in Peril (PIP) has worked with a local landowner to implement an agri-environment scheme creating 12ha of wet woodland. PIP successfully applied for additional funding from Angus Environment Trust and with landowner permissions completed fencing and tree planting along 7km of the Quharity Burn, a main tributary of the South Esk.