The company agreed to set aside plans to turn La Gigoulande quarry in St Peter’s Valley into a new reservoir, after alternative proposals to expand the quarry were set out in the government’s Draft Bridging Island Plan.
However, as a result of doing that, the company has said that an alternative is needed by 2035 as the growing population and climate change could double the shortfall between supply and demand.
‘Our preferred solution for addressing the lack of adequate reservoir storage in the Island would have been the partial conversion of La Gigoulande quarry into a new raw-water storage facility. However, in dialogue with [the] government about the Bridging Island Plan and infrastructure review, we have excluded this option from our recommended plan,’ the utility company’s report says.
Jersey Water’s asset manager Mark Bowden described the quarry decision as ‘disappointing’ but said that the company acknowledged the conflicting demands on the Island’s limited resources. He said the decision presented them with reduced options for addressing the long-term needs for Jersey’s water supply.
‘Fundamentally, the Island suffers from a lack of adequate water storage relative to the demand. We will therefore be looking to provide increased reservoir storage in other ways and in other locations to provide the future resilience that we need. Over the coming five-year period, we will be enhancing our UK-industry-leading leakage and water efficiency performance, and are planning to undertake a further expansion of the La Rosière desalination plant to provide short-term resilience while developing our long-term plans,’ he said.
In its new water resources and drought management plan, Jersey Water says that the combination of the Island’s increasing population and climate change will double the shortfall between available water and the demand in drought years between 2020 and 2035. While the Island’s water supply is currently secure in years of average rainfall, the deficit in supply in the event of a severe drought means the Island would face significant water shortages, according to Jersey Water.
The report also highlights the effect of the historic groundwater PFAS pollution in the aquifer at St Ouen which reduces the reliable supply from boreholes by around one million litres per day to just 0.3 Ml/d. ‘Without intervention, this constraint will continue due to potential changes to the guidance values and regulatory limits for the presence of PFAS in drinking-water supplies,’ the report states.
To ensure the continuation of supplies, Jersey Water proposes a series of measures including delivery of additional reservoir storage capacity by 2045, though no details about how this will be secured are given.
In the shorter term, it proposes water-efficiency measures and leakage reduction to save 0.4 Ml/d and 0.5 Ml/d respectively by 2025. Proposals include temporary water restrictions in times of severe drought designed to save 1 Ml/d, an extension of La Rosière desalination plant by 5.0 Ml/d and working with the government to address the borehole pollution in St Ouen by 2030.
Jersey Water says that the cost of the first phase of its plan (to 2025) is estimated at around £12.5 million of capital investment, with operational costs increasing by around £400,000 per year.
‘Further work is under way to secure capital funding and build an affordable payment plan for all customers that minimises customer tariffs going forward. For the first five years of the plan, the investment in our water resources is calculated to increase the average customer bill by £22, including inflation,’ Jersey Water says.
