Advisory: Blue Green Algae

What is Blue-Green Algae?

Blue-green algae are a type of bacteria commonly found in ponds, rivers, lakes, and streams. They are usually present in low numbers and may not be visible. Under the right conditionstypically warm, shallow, slow-moving water during summer and early autumnthey can multiply rapidly and form a visible scum on the water's surface, known as a bloom.

These blooms may discolor the water to green, blue-green, or brown and can resemble paint, jelly, or floating clumps. Calm weather allows the algae to rise to the surface, and wind may concentrate scum along lee shores.

Note: Blooms don't always release toxins, and their presence doesn't guarantee harmful effects. However, you cannot tell whether toxins are present just by appearance.

Are Blooms Harmful?

Yes, potentially. Some blue-green algae produce toxins that can be harmful to humans and animals if swallowed, inhaled, or contacted through the skin. Effects may include:

• Skin contact: Rashes, eye irritation
• Ingestion: Vomiting, diarrhea, fever, abdominal cramps, joint and muscle pain
• Pets and wildlife: Severe illness or death from drinking contaminated water or licking scum from fur

Children, pets, and vulnerable individuals should avoid contact with bloom-affected water, especially at the shoreline.

What Should Sailors Know?

Sailing can still be safe when blue-green algae are present, provided precautions are taken:

• Avoid shallow water where algae tend to accumulate.
• Perform capsize drills in deeper areas to reduce exposure risk.
• Wear protective gear with tight seals at ankles and wrists.
• Rinse off thoroughly after water activitiesespecially before entering changing rooms.
• Wash hands before eating or handling food.
• Clean and dry clothing and gear completely before storage.

Children and dogs should not play near or in the water, especially where scum is visible. Dogs should be kept on leads and washed if exposed.

Is It Safe to Use the Lake?

• If no bloom is visible, the water is safe for recreational activities.
• If a bloom is present, proceed with caution and follow the recommended safety measures.
• In severe cases, health authorities may close the lake temporarily.

Can the Algae Be Controlled?

Blue-green algae feed on nutrients like nitrogen and phosphorus, often from agricultural runoff. While copper filtration is a known treatment, it is expensive and not guaranteed. The club is actively exploring alternative control options with environmental stakeholders.

To Report a Suspected Bloom:

Please notify a committee member immediately.

Advice compiled in part by Dr. Frank Newton, RYA Honorary Medical Adviser.