Armagh City, Banbridge and Craigavon Borough Council has begun placing warning signs at locations where blue-green algae has been found.

The signs advise adults, children and animals to avoid contact with the algae and nearby water.

Ingestion of affected water may cause stomach upset or serious illness in people and death in animals.

Skin contact can produce rashes and other irritation.

The public is asked to report sightings through the Bloomin' Algae App or via the linked reporting page operated by the Centre for Ecology and Hydrology.

Blue-green algae, also known as cyanobacteria, occur naturally in many inland waters and can multiply rapidly under warm, sunny conditions with elevated nutrient levels.

Some blooms produce toxins; the council states it is safest to assume toxins may be present when blooms are visible.

The council directs residents to the Department of Agriculture, Environment and Rural Affairs website for further guidance.