Protecting one of Eryri's most iconic waterfalls

A development proposal in Eryri (Snowdonia) National Park threatens rare wildlife in a Site of Special Scientific Interest (SSSI)

A planning application has been submitted to build a dam on the Afon Cynfal near Llan Ffestiniog, as part of a hydro-electric scheme. This dam will divert up to 70% of the water away from Rhaeadr y Cwm, the iconic waterfall at Cwm Cynfal, and the change in hydrology that would occur seriously threatens the rare mosses and liverworts that are features of the Afon Cynfal Site of Special Scientific Interest. A similar scheme in Afon Cwm Llechen, just 21 miles away, saw four of five species undergo a decline of up to 43% over a ten-year period. 

Whilst North Wales Wildlife Trust generally supports green energy, the risks that this scheme poses to wildlife is out of all proportion to the small amount of electricity it would produce – merely 600kW, enough for just 60 electric power showers! 

Adrian Lloyd Jones, Head of Living Landscapes for North Wales Wildlife Trust, says: “Considering the small amount of power this proposed hydroelectric power (HEP) scheme would produce, and the declines of bryophyte communities including hornworts, liverworts, and mosses observed following similar HEP scheme elsewhere in North Wales, this scheme poses far too great a risk to the wildlife of Cwm Cynfal. Whilst we support green energy, all developments must be in the right place, and this proposal is clearly in the wrong place.”

Campaign updates

October 2026: The coalition was dismayed that, on 15 July 2026, the Eryri National Park Authority issued a notice to grant planning permission for the scheme. 
The Eryri National Park Authority has since quashed the original planning permission due to a specific legal point having to be addressed as a result of it being raised by the coalition.
This is likely to only be a temporary respite, so we continue to support Cymdeithas Eryri (Snowdonia Society) in its preparation for a Judicial Review that would consider whether the law has been correctly followed with regard to this planning decision. We are also supporting an appeal to raise funds to cover the associated legal costs, estimated to be over £60,000. 

September 2026: We are supporting a call by Cymdeithas Eryri (Snowdonia Society) for a Judicial Review in response to the granting of planning permission for a hydroelectric scheme on the Afon Cynfal, in Eryri National Park.  Find out more: www.northwaleswildlifetrust.org.uk/news/battle-continues-save-one-eryris-most-iconic-waterfalls

January 2026: https://www.northwaleswildlifetrust.org.uk/news/battle-save-one-eryris-most-iconic-waterfalls

Watch drone footage of Cwm Cynfal here