Know the facts about blue-green algae

If you go for a walk around our reservoirs you need to be aware of blue-green algae, how to spot it and what precautions you should take.

The algae occur naturally around the world in reservoirs, lakes and even seawater, and their numbers can increase significantly during warm weather. The algae can produce a bright green or brownish scum, often found floating on the surface or blown to the edges of the body of water. There are different species of algae and some are known to produce toxins which can cause a skin rash or harm animals if they drink the scum in large quantities.

The issue doesn’t affect water supplies because we can take water out of the reservoir at depths where the algae don’t grow, and the water treatment process removes any algae or chemicals they produce. However, we can’t add anything to the reservoir to kill the algae because it is drinking water.

We don’t close off access at our reservoirs but we do put up warning signs about the issue. People and dogs should never swim in reservoirs at any time of the year and we would recommend that people keep their pets on a lead to prevent them drinking the water when there are algal blooms.

It makes sense to be aware of the issue so you can take care, but please continue to enjoy our reservoir estates responsibly.