VISITORS to Sankey Valley Park have been warned to take care after a mat of green weed has grown on parts of the canal, making it look like a green field.

The water surface may appear solid and visitors or animals could mistake the canal for grass or a path.

Warrington Borough Council is warning people to keep a close eye on children and pets who might attempt to walk on the floating weeds and fall into the water.

The canal is covered in a plant called Azolla, which is not native to Britain and has spread from garden ponds.

The weed can grow quickly in warm weather and although it is not poisonous, Azolla can block out sun light to plants in the canal and reduce the levels of oxygen in the water.

Volunteers from Dallam and District Community Angling Group have cleared the weed from some areas of the canal and have installed booms to stop it from spreading quickly.

A small weevil native to north America has been successful in controlling Azolla and this natural way of controlling the weed has no damaging effect to native wildlife and will die once the food source has been consumed.

The council is hoping to release these beetles as soon as they are available and is working with the Environment Agency and the angling group to monitor the situation.