Dredging a polluted lake in St Albans where ducks have been dying could help, according to a district cllr.

Concerns over the future of Verulamium Lake were raised in July and August after nearly 100 ducks were left paralysed or died due to Avian Botulism, a disease caused by ingestion of a toxin produced by bacteria.

The large population of birds, which has increased with people feeding them, contributes to the water pollution, alongside the lake being a “silt trap”.

Park users asked for the lake to be drained and dug out, but green spaces officers suggested at a St Albans District Council local services scrutiny committee meeting on November 5 that the operation would be “extremely expensive”.

Jon Green, parks and green spaces manager, said with the lakes being only one metre deep, in warm weather, they heat up quite quickly, which leads to the conditions we saw this summer with the Avian Botulism.

He said: “As can be seen from the boating lake, [the problem] comes back extremely quickly so dredging isn’t the answer to actually curing it and it would be a short-term and expensive way of dealing with the situation.”

Mr Green went on to explain other ways they could resolve the problem, such as aeration – air circulation.

But Cllr Robert Donald disagreed that aeration would be the right solution.

He said: “That’s going to only tinker with the problem. Dredging actually would help if you create a proper lake.

“It isn’t a proper lake, it’s a pond at the moment with a concrete base which heats up like a soup, a toxic soup, which kills birds and kills fish and so on.

“It is resolvable but it does need quite a lot of engineering and cash to do it.”

The green spaces team have been adding a natural occurring material called symbio on a regular basis to reduce the amount of silt in the lake.

They are currently looking into another scheme, which currently operates on a much smaller lake to Verulamium Lake, which removes the silt, puts it behind baskets filled with stone, and the area where they put the silt behind then has natural plants planted on top of it.

This is said to give natural planting to the lake which in turn will help with the water quality.

Mr Green said: “We need to look at whether this is a transferable scheme to a lake the size of Verulamium and costing it up to see if its viable for the future.

“The other thing we’re doing at the moment is we’ve put out signs out around the lake explaining the wildlife in the park, and one of the things it explains to people is the problem with feeding the birds in the lake and what it does.

“We’ve also had a school competition where school children produced signs asking people not to feed the birds.

“Those signs will sit within a metre or so of the lake, explain about delayed migration and poor health of the birds and pollution of the lake due to overpopulation.”

He added education would work better than having people there stop park users from feeding the birds.

He said: “We hope with the signs we can explain why it’s best not to and if we can reduce the amount of birds being fed that would be a good thing.”