Thurston Outdoor Education Centre: Blue green algae (HABs) policy


  1. Introduction
  2. Venue
  3. Operating considerations

Revised: January 2022


This procedure is for when Blue Green Algae Harmful Algae Blooms (HABs) are observed in the lake, or when a warning has been issued by the Lake District National Park Authority (LDNPA), South Lakeland District Council (SLDC) or the Environment Agency (EA).

This applies to all water activities.

Blue Green Algae Harmful Algal Blooms information below from Freshwater Biological Association, Government and LDNPA websites:

Algae occur naturally in inland waters such as rivers, streams and lakes. When conditions are ideal for growth, an algal bloom can occur. During a bloom, the water becomes less clear and may look green, blue-green or greenish-brown. Scums can form during calm weather when several bloom forming species rise to the surface. This can look like paint, mousse or small clumps. Not all blooms are toxic. Cyanobacteria or 'blue-green algae', a type of blooming algae, can produce toxins at a certain stage of their life cycle. These toxins can kill wild animals, livestock and pets. They can also harm people, producing rashes after skin contact and illnesses including vomiting, diarrhoea, fever, muscle and joint pain if swallowed.

HABs only form in unusually warm water and lack of wind.

Accumulations occur in shallows around shorelines and are clearly visible.


Coniston Water and other lakes.

Operating considerations

If a Blue Green Algae HAB warning has been issued, or if algal blooms are observed then the following actions should be taken:

  • Head of Centre to communicate with LDNPA and other Outdoor Centres to agree best practice which will include:
    • Visiting Staff and adult participants to be made aware of Blue Green Algae situation, policy and precautions in place.
    • Water to be visually checked before any activity involving entering the water.
    • Swimming only to be undertaken in deep water - from boats / craft.
    • Participants briefed not to drink the water.
    • Activities to be stopped, or relocated, if algal blooms appear in the close vicinity.
    • All participants to be advised to shower thoroughly after contact with any possibly contaminated water.