Water pollution

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Blue-Green Algae

Blue-green algae naturally occur in inland waters, estuaries and the sea. There is a wide range of blue-green algae (cyanobacteria). In fresh waters, they're suspended within the water or attached to rocks and other surfaces. Blue-green algae and other algal groups are important contributors to the aquatic biology of fresh and marine waters. They're primary producers that:

  • convert sunlight to energy by photosynthesis
  • release oxygen and carbon dioxide into water
  • take up minerals
  • produce food chain supporting substances

Where high levels of nutrients exist, and other requirements for growth are met - for example, adequate light, mixing, flow and temperature - then the numbers of blue-green algae can increase. It is this increase in numbers of blue-green algae, called blooms, that presents a high risk to water users due to the toxins that can be released. These can cause illness in humans and can kill animals such as dogs.

What to look-out for

Algal Blooms

During a bloom, the water becomes less clear and it may become green, blue-green or greenish-brown. Several species can produce musty, earthy or grassy odours. Blooms can also cause foaming on the shoreline - sometimes confused with sewage pollution.

Algal Scums

Scums form during calm weather when several bloom-forming species rise to the water surface. This can look like paint, jelly or form small clumps. Scums may be blue-green, grey-green, greenish-brown or occasionally reddish-brown.

How can blue-green algae affect me and my pets?

Bloom and scum forming blue-green algae can produce toxins. Not all blue-green algae blooms are toxic but you can't tell by just looking at them so it's best to assume they are and to take suitable precautions. Water-users, particularly children, farmers and pet-owners, should treat all blue-green algal blooms and scums with caution.

In humans - skin rashes, eye irritation, vomiting, diarrhoea, fever and muscle and joint pain have occurred in people who have swallowed or swum through algal scum. Therefore it is important to avoid contact with any suspected areas be it through swimming, boating, diving or even fishing.

In animals - these toxins, which may be produced by the algae, are also poisonous to wild animals, farm livestock and domestic pets. In contrast to humans, animals may eat or swallow large quantities of algal scum that can cause severe illness and death. As algae is not always easy to spot, we recommend dogs are kept out of the water bodies we manage, namely Haysden Country Park and Leybourne Lakes Country Park, for their safety.

It is also important to remember that during times of suspected algae bloom (most common in hot weather when water levels are low) not to let your dog drink the affected water even by the water's edge.

If your dog does come into contact with suspected Blue Green Algae elsewhere, it is advisable to wash their fur with clean water as soon as possible (do not allow them to lick algae off their fur) and contact your vet for advice.

Farmers and other pet owners should also ensure that their livestock do not have access to the affected water.

When in doubt, it's best to keep out!

What can I do?

Don't ignore it, report it!

Call the Environment Agency to report incidents of blue-green algae blooms or scums on their 24 hour incident hotline: 0800 80 70 60

And if the reported sighting is on Council owned water bodies then please inform us on 01732 844522 or by emailing leisure.services@tmbc.gov.uk

Plus in the meantime adopt a precautionary approach and:

  • Avoid swimming near the suspected blue-green algae bloom;
  • Keep your dog on a lead around the area;
  • Ensure that pets or livestock do not have access to affected water.