Blue-green algae naturally occur in lakes, ponds, canals, rivers and reservoirs around the world. However they can produce toxins that are harmful to the health of people and animals. These algae are most commonly seen during the summer months, particularly in calm warm conditions. They are microscopic but clump together in visible colonies up to a few millimetres in size that can rise to the surface and form thin wispy blooms or thick paint-like scums if the numbers are very large.

Both the Environment Agency (EA) and the Scottish Environment Protection Agency (SEPA) provide a blue-green algae analytical service and advice to local authorities, water body owners, managers etc. However there is no routine national algal bloom monitoring system, and so records of past bloom events are patchy. By recording blue-green algal blooms through this app, we hope to get a better overall picture of the timing and location of algal blooms across the UK, to help inform local authorities and relevant health agencies of potential public health risks and aid the EA & SEPA in bloom management and prevention in the future.

The app also asks you for details of what activities you are carrying out in or around the water, as blue-green algal blooms pose a greater risk to water-based activities, such as swimming or windsurfing, compared to non-contact activities such as walking. By gathering details of activities undertaken we hope to gain a better understanding of how algal blooms are impacting recreational use of freshwaters in the UK.