River Ehen

River Ehen willow spiling c) WCRT
England tree planting
England River Ehen
Ennerdale How Hall view - Credit Bas Montgomery
Ennerdale panorama - Credit Bas Montgomery
Ennerdale Sunrise - Credit Bas Montgomery

The River Ehen supports the largest viable population of freshwater pearl mussel left in England. The majority of which are adults.  Surveys indicate that juvenile mussels are present but they are rare and not enough are surviving to offset mortality. The population is therefore ageing and declining and urgent action is required to prevent extinction of this critically endangered population.

West Cumbria Rivers Trust (WCRT), the Environment Agency (EA), United Utilities (UU), and Lake District National Park (LDNP) are funding the PIP project. WCRT is responsible for delivering the project in partnership with the EA and with support of other organisations.

The River Ehen is designated as a European Special Area of Conservation (SAC), designated for Freshwater Pearl Mussels (FWPM) and Atlantic salmon and also as a Site of Special Scientific Interest (SSSI) for FWPM. The river is situated in Ennerdale, West Cumbria and flows from Ennerdale Water, discharging 27 km downstream into the Irish Sea at Sellafield.

The PiP Project will focus on the SAC, which stretches from the outlet of Ennerdale Water to the confluence of the River Keekle in Cleator Moor and the surrounding catchment area.

Restoring habitat

The primary objective of the project is to restore habitats, allowing existing pearl mussel populations to flourish. Habitat restoration will benefit both mussels and salmonids, Atlantic salmon (Salmo salar) and trout (Salmo trutta), on which the pearl mussel lifecycle is dependent.

Actions will include:

a) Better protection and management of river banks by:

  • implementing riparian tree planting and fencing of river banks to improve bank stability and reduce silt input into the river through the use of suitable agri-environment schemes by land managers.

b) In-stream and riparian restoration works

  • identify the in-stream restoration works that will most benefit pearl mussels and salmonids.
  • man-made drainage ditches will be managed to reduce silt and nutrient run-off and improve water quality.
  • small ponds or wetlands will be created where appropriate to intercept enriched run-off before it reaches the river.

c) Encystment of salmonids

Where existing populations of pearl mussels are at risk of being lost entirely, we will focus on securing these populations.

  • In the River Ehen, where pearl mussel populations are too small for recovery to be guaranteed, artificially attaching wild juvenile salmonids with local pearl mussel glochidia will be implemented.

d) Monitoring

  • monitoring throughout the project will look at salmonid and freshwater pearl mussel populations, water and habitat quality.
  • an assessment of potential pollution sources will be undertaken to establish where actions can be targeted to reduce nutrient and silt inputs.

e) Communicating

Providing information about freshwater pearl mussels will help raise awareness and encourage people to protect existing populations.  This is being done through:

  • Pearls in the classroom; an education programme.
  • Raising awareness of the actions taken during the project, and how they can be applied more widely using a range of media and attending events or holding workshops.

Downloads and links