APEM were commissioned by Dŵr Cymru Welsh Water (DCWW) to support the development and management of the site at Llanishen & Lisvane reservoirs.


The future of Llanishen and Lisvane reservoirs has been subject to a decade-long planning saga. In 2013, the site’s previous owner, Western Power Distribution (WPD) lost its appeal to build 324 houses at Llanishen reservoir. Following this, WPD sold both reservoirs to steel company, CELSA UK, who wanted a secure water supply for their steel plant in Tremorfa (CELSA is supplied water from Lisvane Reservoir). 

In 2016, after years of uncertainty, Dŵr Cymru Cyfyngedig – trading as Dŵr Cymru Welsh Water (DCWW) – secured the 999-year lease for Llanishen and Lisvane reservoirs and the surrounding land from CELSA UK. The aim of the acquisition was to safeguard and enhance the reservoirs for future generations. 

Essential maintenance and safety works started in June 2016 to bring the reservoirs up to modern operating standards. In the meantime, an extensive community consultation has been undertaken by DCWW to enable local people to share their views on the kinds of leisure and recreational activities that could be offered there once remediation works are completed.

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Photo of Welsh Water pipe installation site

The site encompasses two Sites of Special Scientific Interest (SSSI) which are of national ecological value:

• Lisvane Reservoir SSSI is designated for its overwintering wildfowl

• Llanishen and Lisvane Reservoir Embankments SSSI is of special interest for its diverse assemblage of grassland fungi including up to 25 species of waxcap

The site also encompasses nine non-statutory Sites of Importance for Nature Conservation (SINC) covering species and habitats such as glow worm, grass snake, common toad, lichen, marshy grassland, wet woodlands and locally rare water plants.

DCWW aims for the site to become a resource for the local community, offering recreational activities for health and wellbeing in addition to supporting the existing biodiversity. The development proposal includes access improvements, landscaping and parking on site. Formal paths around both reservoirs have been carefully designed to guide visitors around the site and protect the areas of highest ecological value. There will be a new visitor hub with a water sports centre, café, a venue for functions and a boat workshop for undertaking maintenance and repairs.

Bird hides and floating islands will be constructed on Lisvane reservoir. This area will become a winter conservation zone for visiting waterfowl (underpinning and supporting the SSSI designation). A further conservation zone will be created in woodland, featuring a learning zone with a Welsh roundhouse to support education and training development.

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The outcomes

Welsh water

Since the site was acquired, APEM have delivered a comprehensive suite of surveys and reporting to support DCWW’s ambitious aims for Llanishen and Lisvane reservoirs. These have included:

  • Ecological Clerk of Works (ECoW) support – from 2016 to present, protecting wildlife and habitats during construction works
  • Badger surveys and advice – recording the presence or absence of badgers and providing management recommendations
  • Grassland fungi annual surveys and assessments – recording the presence and extent of these species, with recommendations for immediate and future management, including an updated condition assessment
  • Lisvane Reservoir SSSI – Condition assessment of the overwintering waterbird interest features of the Lisvane Reservoir SSSI, and overwintering bird surveys
  • Advice and watching brief to protect breeding waterbirds during Llanishen Reservoir drawdown (including ECoW)
  • Fish rescue and translocation – relocating fish due to construction and emptying of reservoirs
  • Glow worm surveys – gathering information on presence and locations of these species
  • Phase 1 Habitat Surveys
  • Crayfish surveys (reservoir and the Nant Fawr watercourse) – presence-absence survey of the signal crayfish invasive species
  • Arboricultural surveys – gathering information on trees on site and their condition and potential safety management required
  • Great crested newts and bat assessment surveys – gathering information on location and presence of these European Protected Species
  • Environmental Impact Assessment Screening Report and Ecological Impact Assessment Report – supporting the development planning application
  • Lichen survey – contemporary lichen survey covering both reservoirs
  • Dormouse Management Plan – long term strategy for the protection of this European Protected Species found on nearby sites
  • Soil Survey and Resource Plan to ensure that the soil resource is managed sustainably as part of development
  • Landscape and Ecological Management Plan – providing detail and specifications for the management of habitats and other features of biodiversity interest in accordance with BS42020:2013 (Biodiversity: Code of practice for planning and development)

Welsh Water flower

The delivery of these services ensured that DCWW have a detailed understanding of the conditions and flora and fauna present at this important site. This will inform future management as well as planning applications for the visitor hub development. We continue to work closely with DCWW and always be on hand with our locally-based field teams to support the delivery of this ambitious and exciting project.