Campaigners against plans for a St Austell Bay desalination plant say an information day they held was so successful they will be holding another such event.

The first Desalination Information Group (DIG) Open Day was held at Par and attracted more than 200 people.

The organisers say they were overwhelmed by the support and engagement demonstrated by people who attended to find out more about South West Water’s proposed desalination plant.

The water company has put forward the idea of having a plant at Par to create fresh water from seawater after restrictions had to be introduced in Cornwall following a lack of rainfall in previous years.

The campaigners said the information event “was so successful we will be holding another open day at Alexander Hall, Middleway, St Blazey on Thursday, April 11, between 4.30pm and 8.30pm for those who were unable to attend previously”.

A DIG spokesperson, talking about the open day in Par, said: “Displays included a detailed map showing potential abstraction and discharge pipe sites (1.5km and 3km respectively) into St Austell Bay and the proposed 13km pipeline route from the plant to Restormel Treatment Works.

“Unlike the South West Water maps, this one also detailed depth contours in the bay and the significant seagrass and maerl beds which are important carbon stores.

“Images of large underwater drilling rigs used by South West Water previously were displayed, plus a ‘mock-up’ model showed the actual size of the proposed marine pipes – a significant 900mm in diameter.”

Alexandra McCabe, who visited the exhibition, said: “Seeing the map of the maerl beds in relation to the proposed pipeline is really alarming. I hadn’t appreciated that maerl stores so much carbon and can be damaged so easily.”

Other displays featured facts and figures researched by DIG, including those questioning the climate statistics quoted by South West Water to justify the proposed plant.

Aileen Ryder, of DIG, said: “South West Water states ‘summers are up to six degrees Celsius hotter and 60 per cent drier in the last 30 years’. I don’t know where this research came from because it’s simply not true for Cornwall!

“If South West Water concentrated their efforts into storing water effectively, improving their infrastructure, mending pipes and fixing more leaks, there would be less anxiety around water security.”

Children made pictures of the marine environment and coloured drawings of seahorses. The event also included display of seahorse art by artists who are concerned about the implications of desalination.

The spokesperson said: “Both the short-snouted seahorse and the spiny seahorse make their home in St Austell Bay’s seagrass and will be threatened by the pipeline construction and the highly-concentrated brine that will be discharged if the proposal goes ahead.”