Blue-Green (Cyanobacteria) Algae

Moray Council is issuing a reminder to people to be on the lookout for blooms of potentially hazardous blue-green algae in the area’s water bodies including rivers and ponds.

What are Blue-Green algae?

Blue-green algae are tiny organisms which occur naturally in lochs, ponds, reservoirs, rivers and in the sea.  They commonly occur during periods of prolonged hot weather but sometimes occur at other times of the year.  Waters which have been polluted by agricultural, domestic or industrial discharges are prone to developing blue-green algae.

In still waters the algae can multiply to such an extent that they discolour the water which then appears green, blue-green, greenish brown or dark brown.  Sometimes a scum may form on the surface.  This scum can appear in different places, at different times, but is most commonly found at the water’s edge or shore line.

How do blue-green algae affect humans and animals?

Some, but not all the blue-green algae produce toxins or release these into the water.  It is not possible to tell which algae do or do not produce toxins simply by their appearance.  Laboratory analysis is needed for this.  Therefore, it is advisable to regard all algal scums as toxic.

The toxins of blue-green algae can cause deaths of animals which come into contact with algae, either through drinking contaminated water or swallowing quantities of scum, or shoreline matter or crust.  Dogs have died after going into the water at the shores of affected lochs.

While the toxins have the potential to kill animals, in humans the effects tend to be less severe but the toxins can cause skin rashes, eye rashes, vomiting, diarrhoea, fever, and joint and muscle pain if ingested or if they come into contact with skin.

We are advising the public, especially people undertaking water sports, anglers and dog owners, to be alert to the blooms as temperatures rise.  If blue-green algae is suspected, people and animals should avoid direct contact and seek advice.

What about eating fish from affected waters?

Blue-green algae and their toxins can adversely affect fish growth and health and, in some circumstances, can cause fish kills.

It is currently thought that eating fish from waters affected by blue-green algae is acceptable, provided that the fish show no behavioural abnormalities and there are no dead fish in the water body concerned.  The fish should be thoroughly gutted and well washed before eating.  You should not feed the liver, other offal, or gut from fish caught in waters affected with blue-green algae to pets.

Monitoring and Advice

Over the warmer months the Private Water Supply Sampling team routinely monitor bodies of water in Moray.

Where monitoring reveals higher than acceptable levels of algal bloom, Warning Notices will be posted at the affected water body.

If you see the Warning Notices or, if you spot an algal bloom:

• Keep yourself, your children, and pets out of the water;
• Farmers should ensure that their animals do not have access to contaminated water.  This may require fencing around suspect waters;
• If you believe you pet may have been exposed to blue green algae then contact your vet as soon as possible to get advice;
• If you do need to go into the water, shower thoroughly once you get home;
• If you need to seek medical assistance for yourself, children, or pets inform them of the circumstances and
• If there are no Warning Notices about, please report it to us (Contact Us details are at the bottom of this page) so we can ensure warning signs are put up.

Currently Affected Sites in Moray

Sites will appear here

Further Resources

NHS / Health Protection Scotland (HPS) -

Scottish Government -

Scottish Water monitors drinking water supplies to prevent any harmful effects on health from blue-green algae.

Scottish Environmental Protection Agency (SEPA) - The Council’s Environmental Health team works closely with SEPA where there are reports of possible blue-green algae growth.  SEPA are the primary Regulator for all pollution related matters associated with the water environment.  Please see the SEPA website for full details.

If you wish to report a serious pollution incident SEPA’s Pollution Hotline can be contacted 24 hours a day on 0800 80 70 60.

Contact Us

Environmental Health
Moray Council
Council Office
High Street, Elgin
IV30 1BX

0300 1234561

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