improving water quality

How to Stop Fish and Wildlife Dying in Your Dam

Follow the below steps for the greatest chance of preventing fish kills and stopping wildlife getting sick or dying in your dam

What causes fish and wildlife to die in a dam?

In absolute simplest terms, it is generally a lack of oxygen in water that is the root cause of animal sickness. As well as being critical to breathing, and blood saturation and circulation, oxygen at its most base level is a cleaning agent. Think about oxidation in rust, how oxygen exposed to an unprotected surface triggers chemical reactions that eat away at metal. In an aquatic ecosystem, oxygen plays a vital role in keeping everything in check, both enabling beneficial processes to take place and disabling non-beneficial processes.

Blue-Green Algae: Dead/Sick Fish and Wildlife

Problem

This is one of the most common causes of health problems in and around waterways. Blue-green algae is not actually algae but cyanobacteria that clump together as millions of tiny pieces forming an oil-slick/paint-spill looking green or yellow mass. These organisms produce toxins that can affect many parts of animal and human bodies. The toxins can damage the liver, kidneys and nervous system among other body parts, resulting in severe sickness and even death.

Solution

Cordon off the area from people and animals. Make sure you’re not using the water for irrigation, spraying the toxins on everything. You can test for blue-green algae using our DIY test kit. Aerate the water with an aerator. You can see in this customer story how an aerator eradicated blue-green algae from a livestock dam. Yes, it will take a few weeks but this is the safest way to treat blue-green algae.

You may be tempted to poison the blue-green algae with an algaecide, but be warned, if you do, there is a chance the blue-green algae will detect it has been poisoned and may release all its toxins at once. This is a worst-case scenario for your water. The safest thing to do is starve the blue-green algae to death through aeration by encouraging “good” bacteria to outcompete the algae. This has a lot less chance of shocking the blue-green algae and triggering it to release its toxins. Instead, the blue-green algae tends to slowly recede until it vanishes. Not relying on an algaecide also allows you to naturally shift conditions in your water so you’re tackling the cause of the problem as well as the symptom. In other words, you’re changing conditions that will greatly limit the chances of you having to deal with blue-green algae next year.

To speed up the processes above, you can also use Biostim. Here is a customer story showing 99% of blue-green algae being eradicated after 11 weeks using Biostim on its own, aka without aeration or any other treatment. For the most effective results, combine aeration and Biostim.

Blue-green algae test kits can also be used post-treatment (after the BGA has visibly disappeared) to detect if there are any toxins left in the water. That way you can see if its safe for animals and irrigation.

How does Biostim improve water quality?

Customer Story

Eradicating blue-green algae and aquatic weeds in 6 weeks with a surface aerator

Watch video

Avalon Nursery near Ballarat was having a problem with blue-green algae and red azolla in one of their irrigation dams. 

We recommended installing a 1.5hp solar-powered Air-O-Lator Carnival Aerating Fountain. Within days of installing the aerator, the blue-green algae and weeds began to retreatAfter just 6 weeks, the algae and weeds were completely gone. The smell had disappeared too.

Mass fish kills

Problem

Mass fish kills, i.e. a lot of fish dying in a short period of time, are often caused by turnover events in highly stratified water. Stratification refers to a layering of sections of water which remain unmixed and of very different composition. Usually the top layer is warm and has a decent amount of oxygen in it, while the bottom layer is cold and has very little oxygen in it. In this situation, all the fish will be living up near the surface. Sometimes this bottom layer makes up the vast majority of the water body. This is very dangerous if the water layers are forced to suddenly mix and the oxygen is diluted to a point where fish can’t access enough of it. This is what happens in turnover events, often after extreme weather, e.g. following hot, still, overcast conditions. The layers break apart and mix and the oxygen is spread so thin that your fish don’t have access to enough oxygen, leading to everything dying at once.

Solution

Add more oxygen to your water using an aerator. There are two ways to go with this: a surface aerator or a sub-surface aerator. Surface aerators are good for shallower dams because most of the activity happens at the surface. They are also ideal for emergency aeration, i.e. adding oxygen to your water as soon as possible. Sub-surface aerators are better suited to deeper water bodies and may be a little slower at getting your oxygen levels up, but they are more effective at breaking apart stratified layers because the bubbles start from the floor and travel up, thoroughly mixing the water. Surface aerators mix the water as well, but are less effective at breaking deeply stratified water.

surface

Surface aeration

Surface aerators sit on the surface of the water and use a propeller to pump water up into the air. This allows for gas exchange between the water and the air where oxygen enters the water before it returns to the waterbody. Agitating the surface of the water also creates a ripple effect which increases the surface area of the waterbody. More surface area means more gas exchange, resulting in greater aeration.

Shallow water

90%

Deep water

30%

Speed to aerate

85%

Power consumption

70%

Suitability for swimming

20%
sub-surface

Sub-Surface aeration

Sub-surface aerators involve using air-stations (often multiple) set up on the floor of your dam. These systems pump out air which becomes bubbles. These bubbles rise to the surface, getting larger and larger as they climb. This drags less-oxygenated bottom-waters to the surface where oxygen can enter the water. When the water becomes more oxygenated, it gets heavier and sinks, producing a circulating system.

Shallow water

30%

Deep water

90%

Speed to aerate

50%

Power consumption

40%

Suitability for swimming

89%

How does aeration improve water quality

Dead Livestock/Wildlife–E. coli or botulism

Problem

E.coli and botulism can also hurt and kill livestock and native wildlife by damaging the intestinal areas of their bodies. The same condition can occur in people. It will be difficult to know if E.coli is present without a lab test but fortunately the solution to treating your water is the same.

Solution

Like above with blue-green algae, cordon off the area from people and animals, and ensure you’re not using the water for irrigation. Add an aerator to the water and treat with Biostim probiotics. The goal is to ramp up production of “good” bacteria who can outcompete the harmful E.coli or botulism. The harmful bacteria won’t survive long when conditions change, i.e. “good” bacteria populations grow, nutrients fall, and the E.coli or botulism are starved to death. Aeration also helps circulate and move the water which better exposes the “bad” bacteria to the cleansing effects of the Sun’s UV.

expert Advice

Need help? I'm Scotty Tucker and I offer FREE advice

I'm happy to take a look at your dam [on Google Maps] and provide FREE advice on the right type of aerator, motor size and placement. I can also answer any questions you have on improving water quality.

"Since WQS installed the aerator, we've not had a single algae problem. In our smaller ponds that are too small for aerators we used Biostim pellets on their own and have noticed a huge reduction in algae.”

Andy Hart

Horticultural Curator—Department of Environment, Water and Natural Resources, Adelaide

“We had a nutrient-rich stormwater lake that was having continuous problems with algae. We were previously treating the nutrients with a liquid solution that would just end up getting flushed away with the outgoing water. Scott recommended we switch to Biostim pellets which were exactly what we needed.”

Giles Pickard

Environment Project Officer, City of Subiaco

“Visiting ducks and our pet geese were continuously fouling the dam. WQS recommended a number of systems to improve the water quality. We are very happy with our final choice, the windmill aeration system. This combined with the Biostim pellets and liquid are cleaning up the dirty dam. Everything WQS said would happen has happened!”

Greg Lewis

Canterbury, Victoria

“We had an urgent problem—our old irrigation system had blockages from weeds. Our dam was also riddled with black sludge. Scott recommended both aeration and biologicals and within six weeks the dam became so clear I could see to the bottom of it for the first time in years! I was chuffed that we could fix the issue without the use of chemicals.”

Michael Grant

Owner, Grant’s Citrus Farm
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