MONDAY, 29 JUNE, 2026

For immediate release.

Public urged to be aware of blue-green algae in waterways this summer

As temperatures rise, NHS Tayside is reminding people across Dundee, Angus and Perth & Kinross to be aware of potentially harmful blue-green algae in lochs, ponds, rivers, reservoirs and coastal waters.

Blue-green algae are tiny organisms which develop naturally in waterways. The algae can multiply during the summer months and discolour the water which then appears green, blue-green or greenish brown and, occasionally, they clump together to form a scum on the surface of the water. At the shoreline, algal crusts may appear brown to almost black in colour.

People and animals can be affected as a result of direct contact with water affected by blue-green algae and NHS Tayside is advising the public, especially people undertaking water sports, anglers and dog owners, to be alert to the blooms as temperatures rise.

Swimming in, touching, or accidentally swallowing water affected by blue-green algae can cause symptoms including:

• Skin rashes

• Eye irritation

• Vomiting or diarrhoea

• Muscle and joint pain

While symptoms are usually mild, they can occasionally be more serious.

Dr Emily Stevenson, Consultant in Public Health Medicine for NHS Tayside, “During warmer weather, we routinely monitor for blue-green algae because of the potential health risks to people and animals. Anyone who notices discoloured water, surface scum or other signs of a potential bloom should avoid contact with the water and keep pets away.

“Warning signs are put in place where blue-green algae blooms have been identified at levels that may pose a health risk. However, blooms can develop quickly and may be present before warning signs are installed, or in locations where they have not yet been reported. People should not assume that water is free from blue-green algae simply because there is no warning sign in place.”

Anyone who finds a loch, pond or river which they suspect is affected by blue-green algae and which is not displaying a warning sign, should contact their local environmental health service or can report the presence of Blue-Green algae using the Blooming Algae App.

Contact:

NHS Tayside Communications

(01382) 424138