Blue-green algae season - public asked to be cautious

Blue green algae cliff 02 sml

Blue-green algae can be present in lochs and other water bodies in Shetland, especially in warmer weather, and people are asked to exercise caution where blooms can be seen.

Dogs and livestock should be kept away from these lochs to prevent any potential health effects. The public are advised not to bathe in any affected waters and fishermen should also exercise caution.

Anyone coming across any suspected algal blooms is encouraged to make any reports (photographs can also be uploaded) using the ‘Bloomin Algae’ app.  This is available to download from a link online at the UK Centre for Ecology & Hydrology .

SEPA and local authorities will receive alerts when local blooms are reported via the app.  These details will then be assessed remotely and a judgement made as to whether it is blue-green algae and if a sample of the water should be taken.

If officers are confident from the visual evidence or analysis that it is a blue-green algal bloom, then appropriate action and warnings will be issued locally. Any affected areas identified in this way will be listed on the Council's Environmental Health webpages

The public can report any sightings directly to SEPA via their online form at or by calling their Pollution Hotline on 0800 80 70 60.

or to the SIC Environmental Health Team on 01595 745250 or by emailing or via Facebook.


  • Blue-green algae exist in fresh waters across the UK and throughout the world; they are noticed when their concentrations increase to form "blooms" and when they form scum - looking like blue-green paint – which can collect on the shore line.
  • Direct contact with blue-green algae may lead to skin rashes, eye irritations, vomiting and diarrhoea, and fever and pains in muscles and joints. Toxic algae has caused deaths in livestock and dogs.
  • Water supplies are treated to remove blue-green algae and additional treatment may be applied to destroy or remove toxins should they arise. The actions currently taken are precautionary.
  • The behaviour of blue-green algae is very erratic. The level of its toxicity can fluctuate, it can appear one day, be dispersed by the wind but then re-accumulate and grow quickly again at any time.


Published: 8th July 2021