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Where does Aberystwyth's drinking water come from

By Rudi Winter

For a gentle start to the season, I had a stroll up the service track SN7687 : Drosgol across Nant-y-moch reservoir by Rudi Winter to Llyn Llygad Rheidol SN7987 : Llyn Llygad Rheidol and the north face of Pumlumon Fawr by Rudi Winter from Nant-y-moch SN7787 : Eastern shore of Nant-y-moch reservoir by Rudi Winter. I knew that the beautiful glacial lake tucked away on the north side of Pumlumon Fawr SN7987 : Dam, Llyn Llygad Rheidol by Rudi Winter was part of Aberystwyth's drinking water supply, but I hadn't appreciated quite how important it is in this respect. During the walk, I had a rummage around the dam SN7987 : Llyn Llygad Rheidol dam by Rudi Winter SN7987 : Dam re-enforcement, Llyn Llygad Rheidol by Rudi Winter and spillway SN7987 : Spillway, Llyn Llygad Rheidol by Rudi Winter SN7987 : Spillway, Llyn Llygad Rheidol by Rudi Winter and on the way back investigated a stream abstraction point on the Maesnant SN7787 : Sluice and water abstraction point by Rudi Winter, which tops up the water supply.

Back at home, I read up on how the drinking water supply of the region was developed over the years as well as on drought plans in the event that we get an unusually "nice" summer. Here's the story:

North Ceredigion is supplied with drinking water through the water works at Bont-goch SN6886, which are fed with raw water from the Llyn Llygad Rheidol SN7987 : Dam and spillway, Llyn Llygad Rheidol by Rudi Winter and Llyn Craig-y-pistyll SN7185 : Dam and jetty of Llyn Craigypistyll by Rudi Winter reservoirs. The supply is supplemented by stream abstractions from the Maesnant SN7787 : Sluice and water abstraction point by Rudi Winter and the Nant y Moch SN7686 : Pumping station by the Nant y Moch by Nigel Brown (photo: Nigel Brown) as well as two groundwater bore holes near Lovesgrove SN6281.

Llyn Llygad Rheidol is a natural lake in a glacial hollow on the north face of Pumlumon Fawr which has been dammed to increase capacity. Aberystwyth Town Council, then responsible for water supply to the town, built a 16-mile pipeline to transport untreated water from Llyn Llygad Rheidol directly to Aberystwyth in the 1870s.

The separate Aberystwyth Rural District Council, serving the villages of north Ceredigion, took a water supply from the Afon Leri, regulated by their dam at Llyn Craig-y-pistyll. They also built the treatment works at Bont-goch in 1939.

The two local authorities had begun to make joint plans when the responsibility for the water supply was transferred to the new Cardiganshire Water Board in 1962. In 1967, the water board built a new pipeline connecting the two reservoirs, siphoned around the base of the Nant-y-moch hydroelectric reservoir, which had been built between 1957 and 1961. This new pipeline replaced the old direct one to Aberystwyth to allow processing of all drinking water at Bont-goch. LinkExternal link

The water from the two small reservoirs is generally sufficient to supply the needs of north Ceredigion. Dŵr Cymru, the publicly owned water company now in charge of water supply to the area, has a drought plan which establishes that the supply would be topped up by transfers from Nant-y-moch directly into the pipeline linking the two drinking water reservoirs using a temporary installation during a severe drought LinkExternal link . This has not been necessary to date.

You can see this trip plotted on a map on the Geo-trips page LinkExternal link .
Trip profile: LinkExternal link


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Tue, 31 Mar 2015 at 18:55
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