Two weeks ago, as parts of the north of Scotland experienced their coldest minimum temperatures in 25 years, Scottish Water’s water operations team faced a battle to keep water flowing for communities in the Western Isles and parts of the north-west Highlands.

With intakes from supply lochs starting to freeze up after sustained sub-zero temperatures, the water company called upon the help of professional divers - more used to working in seawater to inspect and maintain salmon cages and feed barges, than working around the clock in icy inland lochs.

The biggest challenge of all was faced by Benbecula-based NDUS at Lochmaddy in North Uist, where two dive teams maintained a constant watch for over 48 hours from the early hours of Friday morning until Sunday. Only then was there confidence that stable supply of water from Loch Fada to Lochmaddy Water Treatment Works had been restored.

Mark MacInnes of NDUS, one of the original team of four divers who were on site from the early hours of Friday morning until Saturday commented:

“We had been called out to the Water Treatment Works after returning from another job on Thursday evening, but we checked everything at that time and the pumping station was operating okay. We had said we would come back out at any time if our help was needed and we got a call at 2am.

“Usually it’s seawater we’re working in, so the temperatures don’t go much below around 6 degrees Celsius, even in winter. The water temperature in Loch Fada overnight was down between -3 and -4 degrees Celsius.

“We only had about four inches of visibility in the loch during the daytime, and even less at night, so we had to find and clear the intakes using our hands - but you lose a lot of feeling and dexterity at that kind of temperature which makes it harder."

The divers worked around the clock in the challenging conditions to keep the water intakes clear at Loch Fada.

Temperatures fell even further below freezing overnight - Mark MacInnes continued:

“There are filter screens at the end of the intake pipe that extend on either side, with fine holes to stop debris being drawn into the pumps. As soon as slush from the loch was coming into contact with the screen, the holes were icing over.

“As we worked through the night, one side of the screens was freezing over as fast as you could clear the other. We set up a net around the screens with ropes to the surface, which helped slow down the formation of ice and reduce the frequency of having to go into the loch. That meant we could get up to the Water Treatment Works and get warm in between dives. We just had to keep watching the flow into the pumping station to know when we had to go and clear the screens again.”

With the divers keeping the intake clear, Scottish Water’s team worked to maximise production of drinking water at the site, brought in extra supplies by road tanker and overcame challenges at neighbouring Water Treatment Works in South Uist and Benbecula, where NDUS also provided support.

Scottish Water’s Water Operations Team Leader Peter MacNab said:

“The situation we faced two weeks ago was a real test for our dedicated local team. The duration and the extent of the challenges we faced across the islands called for a marathon effort. The commitment of our people to the essential role we play, and to finding solutions under pressure, was critical to success over four very long days and nights.

“When we most needed it, we couldn’t have asked for stronger support from so many local businesses and partner organisations. I particularly want to recognise the extraordinary effort of the divers from NDUS to get the water flowing again for our customers. The photos of the conditions they worked through speak for themselves.”