At the end of November, after months of very low rainfall, reservoir levels had fallen to 46%, leading Jersey Water to turn on the desalination plant at La Rosière – between La Moye Prison and Corbière – for the first time in seven years.
Chief executive Helier Smith said the latest readings taken on Monday showed that overall reservoir levels were at 92.1%. This situation puts the company on target to meet its optimum full
capacity by 1 April in preparation for the traditionally drier spring and summer periods.
‘We have made quite big gains since the beginning of the year even though January had a very low rainfall,’ he said.
‘The five-year January average is 151mm and this year only 62mm fell, which is less than half of what we would normally expect, so it does not make a good case for ground-water levels.’
Reservoirs are partly filled by streams which naturally rise from the Island’s underground water tables. Jersey Water also has extraction points at streams around the Island to capture water during heavy rainfall which would otherwise flow out to
sea.
‘The long-range forecast for the next three months is showing weather conditions more in line with the average, so from our perspective we would expect reservoirs to probably be at full capacity by the end of March,’ Mr Smith said.
‘At the moment we are in a healthy position, but we need to get an indication of the water and [surface] stream flows in the spring.’
The company turned off the desalination plant in the week before Christmas and when the final reading of 2018 was taken reservoirs were 69.7% full, compared to 98.7% the previous New Year’s Day.
It costs £5,000 a day to run the plant, which uses a reverse osmosis process to remove salt from seawater and pump it to Val de la Mare for further dilution before being pumped to the five other reservoirs. It can produce 10.8 million litres a day and the Island’s average daily consumption in winter is 18 million litres.
