Dealing with Blue-Green Algae 

Blue-green algae (or cyanobacteria) occur in fresh, brackish and sea water throughout the world; in the UK they can sometimes appear in large blooms during the summer months in ponds, lakes, reservoirs and old gravel pits.

While usually green, or blue-green in colour (hence the name), they may be khaki, blue, black, dark brown or red. Blooms of blue-green algae can form thick scums on the surface of the water and are often cause for concern because as they start to break down they can release a range of toxins. If these toxins are ingested in large quantities they can present risks to human health and long-term exposure of human skin to the toxins can cause irritation. The effect on humans in the UK has been limited to illness rather than death and there are a number of steps that you can take to minimise the risk associated with blue-green algal blooms.

There is a wide variety of types of blue-green algae and the fact that each of them can behave differently means there are no strict guidelines on whether it is safe to continue using recreational waters in the event of an algal bloom. Instead, it is recommended that a risk assessment be made on a case-by-case basis to establish what is necessary to protect the health of water users.

The RYA has therefore produced a guidance note (available to download to the right of this page) for those clubs wishing to continue operating on their water if blue-green algae are present. Aimed at sailors in general, it also applies to windsurfers of RYA Level 3 and above. All the evidence is that windsurfers of this level of competence are likely to spend no more time in the water than the average dinghy sailor.

Each club is of course responsible for making its own decision as to the use of its water, according to the exact circumstances of its case and level of contamination. The RYA can do no more than advise generally on this part medical, part scientific and part legal problem.

The basic principle to be borne in mind is that if sailors and windsurfers of sufficient maturity understand and accept the dangers involved and decide that they wish to continue to sail at their own risk, they may be permitted to do so by the club without the danger of legal liability to the club arising, provided they have been fully appraised of the risks. It may be advisable that activities should be limited to persons aged 14 and over.

The leaflet also contains a section of advice for those teaching children.

Further information on blue-green algae and its impacts on recreational users can be obtained from the RYA Guidance Note downloadable from the right hand side of this page.