The Reservoir Action Group (RAG) was founded on 4th December 2001 to fight plans by an American owned company, Western Power Distribution, which planned to build a large housing development on the site of Llanishen Reservoir in North Cardiff. The aims of RAG are:
- To oppose any building development on Llanishen and Lisvane Reservoirs and the open land surrounding them and to campaign against any application for planning permission on this land.
- To campaign for the area to be given legally protected status and enhanced as a part of the Nant Fawr Green Corridor, so that it can be passed down as a heritage to future generations.
In September 2013, Western Power abandoned their plans to build on Llanishen reservoir and sold the site of Celsa Steel UK, which uses the water from Lisvane Reservoir at its Castle Works in Cardiff Bay.
On 20th January 2016 it was announced that Celsa had granted a 999 year lease for the reservoir site to Dwr Cymru / Welsh Water who announced that it hoped to refill Llanishen reservoir and allow public access to the area once more. Thus it looks as though RAG may have sucessfully achieved its two initial aims.
The reservoirs and their surroundings are an area of outstanding nature conservation importance. Lisvane reservoir is a Site of Special Scientific Interest (SSSI) designated in 1972 for its wintering wildfowl, and the embankments of both reservoirs are a separate SSSI for their internationally important diversity of grassland fungi. Llanishen Reservoir is also a listed structure of historic importance as a key part of the Victorian Taff Fawr scheme to bring water from the Brecon Beacons to Cardiff.