RECENT rainfall has led to increased water levels at the Island’s reservoirs, but Jersey Water has warned that stocks remain below the average late-October figure for the past decade.
Wet weather, including torrential rainfall that accompanied Storm Austen’s passage across the Channel Islands last weekend, has seen reservoirs fill to 63.1% of their maximum capacity – a rise of 7% since 19 October.
Mark Bowden, head of water resilience and emergency planning, said that while the rain was welcome, stocks were still around 160 million litres below the ten-year average, the equivalent of around eight days’ supply for the Island.
“We will need above average rainfall over the winter to replenish stocks ahead of next spring and summer,” he said.
“We’re continuing to encourage Islanders to use water wisely, and the wetter weather is a great opportunity to collect rainwater in water butts, ready to use for garden watering during drier months.”
We will need above average rainfall over the winter to replenish stocks ahead of next spring and summer
Mark Bowden
As well as being Jersey’s hottest summer on record, the three-month period between 1 June and 1 September was significantly drier than average, according to figures provided by Jersey Met. A total of 106.9 millimetres of rain was recorded at Maison St Louis in St Helier, compared with the average between 1991 and 2020 of 158mm.
After last month brought around half of an average September’s rainfall, October has been a wet month, with Jersey Met recording 150.6mm of rain at Maison St Louis by 9am on Monday, and 197mm at Howard Davis Farm in Trinity. The 30-year average figures for the two locations are 106.6mm and 117.3mm respectively.
The lack of summer rain prompted a decision by Jersey Water in late August to activate its desalination plant, La Rosière in St Brelade. Having been switched on, the facility was operating at around half its full capacity in making 5.5 million litres of drinking water per day from seawater.
Upgrading La Rosière forms a key part of Jersey Water’s 2026-2030 strategy, with recruitment of a team for this project having been started in August. The intention is to increase the capacity of the plant, which dates from 1979 and was extensively upgraded in 1999, by 50%.
Largely dry, less windy conditions are forecast for the remainder of October.
