WATER activities have been suspended on Llandrindod Lake until Saturday after an outbreak of algae bloom resulted in the deaths of multiple fish.

The scorching weather Powys has experienced this week – which included Wales’ hottest ever day on record on Monday (July 18) when a temperature of 37.1C was measured in Hawarden, Flintshire – made its mark on the town made famous by its healing waters and spas during the Victorian era.

Lakeside Boathouse, operators of the lake, said the hot weather had dramatically impacted aquatic life in the lake, leading to oxygen depletion overnight on Tuesday and the death of scores of fish. Lee Percy, manager, of the venue, announced on Wednesday that the lake would be closed today and Friday while they work with the authorities to restore the oxygen levels.

“Due to an incident on the lake overnight there will be no water activities until further notice. Sorry for any inconvenience caused,” the boathouse operators announced on their Facebook page.

To dispel rumours that the lake had been closed due to some sort of human tragedy, they posted an update later, saying: “It’s a water quality issue no-one is hurt and we will keep you all posted.”

County Times: Llandrindod Lake from above. Picture by Luke Davies Llandrindod Lake from above. Picture by Luke Davies

Later on Wednesday afternoon, Lee took to Facebook to post a video of the clean-up operation and explain the action being taken. “There was a case of oxygen depletion overnight due to the hot weather we’ve been having,” he said.

“We’ve got a bit of an algae bloom. Luckily, it’s not a blue-green algae one so as of Saturday all activities will resume on the lake.

“A lot of fish have died over the last 24 hours. None of the big fish are dying, however, there are a lot of concerns this could happen. Llandrindod Fishing Club have been working really hard with the boathouse team and Powys County Council to make sure we do as much as we can.

“We’ve got big pumps on the lake, which have been set up to try and put more Oxygen in the water to help the fish overnight. We’ve lost a lot of fish and are losing more, mainly small fish. Overnight could be a big issue

“We’ll be open Saturday for all water activities as planned but we are closing Thursday and Friday to allow the fish to rest and hopefully get the lake back to where it needs to be.”

A spokesperson for Powys County Council said: “Oxygen levels at Llandrindod Lake significantly dropped on Tuesday night/Wednesday morning due to the extreme hot weather and this is having an impact on the fish population.

“Water pumps have been brought in to circulate the water and to get more oxygen into the lake.

“Officers from Natural Resources Wales have been on site to carry out temperature and oxygen level readings and have provided advice to help manage the situation.”

The same issue affected the lake last August, resulting in it being shut for a month. That was, however, an outbreak of the more toxic blue/green algae.

The build-up of blue-green algae is a natural occurrence which happens during warmer months.

The algae produces toxins which can cause skin rashes, nausea, vomiting, stomach pains, fever and headache if swallowed. Occasionally it can cause more serious illness such as adverse effects on the liver and nervous system.

The blue-green algae, also known as cyanobacteria, occur naturally in inland waters, estuaries and seas and cannot be removed or treated. They thrive in warm conditions and are likely to come and go throughout the summer season.