Combatting Blue-Green Algae in Your Dam: A Comprehensive Guide
Blue-green algae might seem harmless at first glance, but it poses a major health risk to people and wildlife in and around the contaminated water. As a dam owner, understanding what a blue-green infestation looks like compared to other algae infestations is essential to ensure you know when to take things seriously. For instance, a normal algae infestation might be a nuisance, but it’s not a major health hazard. This is not the case for blue-green algae. If you have blue-green algae, you need to vacate the area immediately and start treatment.
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What is blue-green algae?
Blue-green algae, also known as cyanobacteria, are organisms that thrive in freshwater environments like dams.
Despite the name, blue-green algae isn’t a true type of algae since it forms as bacteria capable of photosynthesis. This unique characteristic is what gives them the blue and green tint when they produce energy from sunlight.
Under favourable conditions, blue-green algae can reproduce quickly, leading to algal blooms that cover large areas of your dam. And it’s not just that they are visually unappealing, they can also have serious consequences for long-term dam health.
You can spot the following signs of blue-green algae:
- Blue-green, brownish scum on the water’s surface
- Foul or musty odour on sunny days
- Slimy or mucilaginous texture
- Green water
- Foaming across the shoreline
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The threats of blue-green algae on dam health
Understanding the threats of blue-green algae is essential for choosing the right treatments for your dam.
Here are the common risks of these infestations:
Water quality degradation
Blue-green algae can rapidly multiply and form dense blooms on the water’s surface. As they grow, they release toxins and organic matter into the water. This can lead to a noticeable decline in your water quality.
You might notice foul odours and murky, discoloured water. Poor water quality has a detrimental effect on aquatic life and makes the dam unsuitable for swimming, fishing and other recreational activities.
Harm to aquatic life
The toxins produced by blue-green algae, specifically microcystins and cyanotoxins, harm fish, plant species and other organisms that thrive in your dam. Since algae are constantly producing toxins, fish will eventually due and disrupt the natural balance of your ecosystem. In turn, you might find it more challenging to maintain a healthy aquatic environment.
Human and animal health risks
Blue-green algae infestations can also pose a risk to human and animal health. Coming into contact with or ingesting algae could cause various health problems, such as skin irritation and gastrointestinal problems.
Pets and livestock in the surrounding areas of your dam may also be vulnerable to these risks if they come into contact with the infested water.
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Treating blue-green algae
Warning: blue-green algae is toxic. Make sure you…
- Do NOT have any skin contact with water contaminated by blue-green algae
- Do NOT let any animals drink from contaminated water
- Turn OFF any equipment such as fountains, pumps, sprinklers that may cause the infected water to mist over land. If this can’t be avoided, e.g irrigation, then irrigate at a time of day that avoids human contact.
- Do NOT use infected water to irrigate food crops that are close to harvest or that may hold water e.g leafy greens.
- Wear PPE if concerned about spray drift.
- Do NOT eat or rub your eyes/nose/mouth before washing your hands thoroughly.
- Do NOT eat fish or crustaceans caught from an infected water body
If you suspect you have blue-green algae, it’s best to first assess what the water is used for and how quickly you need to use it. If you have the luxury of time, then implementing aeration and a probiotic like Biostim to change environmental conditions and introduce competing (beneficial) species will give you the best chance of getting rid of the blue-green algae without it releasing its toxins.
If you need to use the water quickly and thus remove the algae quickly, then you need to look at algaecides. With algaecide use comes a risk because some blue-green algae release toxins when ‘attacked’. So, while you may visibly get rid of the blue-green algae in the water, you may also end up with toxins in your water that can’t be seen. Note: you should use fresh water (not from the dam) when diluting the algaecide, so any spray drift is free of toxic algae.
How to prevent blue-green algae
Preventing the growth and spread of blue-green algae is the first line of defence to maintain a healthy water ecosystem. Implementing proactive measures can help keep your dam free from stubborn algae.
Consider these preventative strategies below:
Regular dam maintenance
Proper dam maintenance is essential to minimise the conditions that encourage blue-green algae growth. You should regularly inspect the dam’s structure, including checking for leaks, erosion or ineffective water flow. A well-maintained dam is more likely to encourage healthy nutrient levels that prevent algae.
Nutrient control
Blue-green algae thrive on nutrients such as phosphorus and nitrogen. You can adopt agricultural and landscape practices to prevent nutrient runoff from entering your dam. For example, maintain a buffer zone of native vegetation around your dam to filter out excess nutrients
You should also avoid over-fertilizing lawns and fields near the dam since more nutrients can reach the water.
Effective water management
Consistent water management protects your dam in the long term. Implement strategies such as periodic water circulation or flushing to disrupt stagnant water conditions that foster algae growth.
You could install an aerator to oxygenate the water and deter algae formation.
Reduced sunlight penetration
Blue-green algae require direct sunlight for photosynthesis. Reducing sunlight penetration in the water can impede their growth. Consider using eco-dyes to darken the tint of your water and reduce UV penetration.
Monitoring and early detection
Regularly monitor the water quality of your dam. You should notice any changes in colour, odour or the presence of scum floating on the surface.
Early detection of blue-green algae is essential for preventing its rapid growth by addressing the problems quickly.
Here are some early signs of blue-green algae
- The water starts to take on a green, bluish-green or even reddish-brown hue
- Surface scum with an unpleasant odour
- Small green algal clumps
- Fish presenting unusual behaviour like swimming near the surface
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Natural treatment options for your dam
When it comes to preventing blue-green algae in your dam, natural methods are effective without harming the environment.
Check out some natural algae treatment options below:
Beneficial microorganisms through probiotics
You can introduce certain types of bacteria into the water to outcompete blue-green algae for nutrients. These microorganisms help break down organic matter, reducing the number of nutrients algae need to thrive and grow.
Probiotic treatments are best for feeding your water. They are 100% natural and can reduce infestations without harming your dam’s ecosystem.
Some probiotic products you can get include:
- Biostim Tablets
- Biostim Powder
- Biostim Liquid
- Biostim Pellets
- Biostim Accelerator
- Nitrifying Bacteria
Aeration
Aeration involves increasing oxygen levels in the water, inhibiting the growth of blue-green algae. Installing aerators, such as a fine bubble air diffuser, can maintain proper oxygenation in your dam. These systems also disrupt the water’s surface, preventing the formation of calm, stagnant areas that favour algal blooms
You can also invest in non-weighted tube diffusers and aerating fountains that help oxygen penetrate deeper into the water.
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