Introduction
G-MW is responsible for the management of blue-green algal
blooms within our storages, irrigation channels and drains.
G-MW regularly monitors and
inspects water bodies within our area of operation for blue-green algae.
A hotline has been set up to
provide up-to-date information on blue-green algae throughout G-MW's region. All queries, requests for information, or suspected
sightings should be directed to G-MW through this hotline on (03) 5826 3785.
For current warnings click here.
Warning signs are erected at major
recreational areas at waterbodies that have high levels of blue-green algae, in
order to assist in alerting the public and to warn against water activities
that involve direct skin contact.
Letters are sent out to G-MW's
customers, and media releases are sent to newspapers, television and radio
stations to inform the wider community that there are high levels of blue-green
algae.
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Algae Awareness
Algae are a diverse group of
mostly aquatic plants that can be found in both salt and fresh water. One type of algae, known as blue-green algae,
has the potential to be harmful as they can make people and animals sick. See (Blue-green Algae Toxins and Symptoms)
Blue-green algae are not plants but are actually photosynthetic
bacteria. The technically correct term
for them is cyanobacteria, however
they almost always more commonly referred to as blue-green algae.
Not all algae are dangerous.
There are many types of algae that can cause the water to change colour
but are just harmless plants. The only
way to tell is to look at a water sample under a microscope.
To complicate things, high levels of blue-green algae do not always
colour the water blue or green. The
water can look yellow, brown, red, blue or green, or there may be no visible
colour change at all.
An earthy, musty or sulphuric smell may accompany high levels of
blue-green algae, however high levels of blue-green algae may be present when
there is no obvious smell at all.
In low numbers, algae are not
usually a problem. In fact, they are an essential part of a healthy body of
water, as they produce oxygen and are themselves a source of food for certain
aquatic animals.
High levels of algae can affect
water quality by causing peculiar tastes and odours, discolouration and
unsightly scums. Algae can be a nuisance
as they can be present on the sides of tanks and drinking troughs and may be in
thick, tangled masses in low-lying swampy areas. Algae can also clog filters, meters, valves
and trickle irrigation lines.
When algae is present in very
high numbers, water quality can be severely affected as when they die, the
decaying algae may reduce the amount of oxygen dissolved in the water and cause
aquatic animals to struggle to breathe and maybe even die.
When blue-green algae die they
release toxins directly into the water.
The toxins in blue-green algae can be poisonous to humans and animals. See Blue-green Algae
Toxins and Symptoms )
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Contributing Factors for Algae Growth
Several factors can
influence the growth of algae, including:
- Weather
-
Light availability
-
Flow/Turbulence
- Algae Food (nutrient) Levels
-
Algae Predator Numbers
Weather ~ Long sunny warm days with no wind are most favourable for algae growth,
although high levels of blue-green algae have been known to persist through
winter. Therefore, if a warning is present, a few cloudy cold days may not
significantly reduce blue-green algae levels.
Light ~ Algae need sunlight to grow and to make their own food. When the water is turbid (has a lot of
soil/dirt in it) the algae find it difficult to get the sunlight they need,
therefore clear water is more favourable for algae growth.
Flow/Turbulence ~ Still
and stagnant water bodies are more favourable for algae growth as the algae are
able to absorb the sunlight they need to grow.
In large lakes stratification of water can occur, this usually means there is
warm water in the top layer of lake and cold water at the bottom. The warm stagnant top layer is favourable for
algae growth.
High levels of blue-green algae may still be present in turbulent waterbodies
with high flow as the algae may grow in stagnant areas and then be transported
into the high flow turbulent areas. For
instance, high levels of blue-green algae may be present in a fast flowing
river, as the algae may grow in a stagnant lake and then be transported down
the river.
Algae Food (nutrient) Levels ~ Many of our lakes and waterways have become enriched with algae food (Nitrogen
and Phosphorus). This may have occurred naturally or as a result of human
activities. The greater the levels of
algae food, the greater the chance of algae growing in large numbers.
Algae Predator Numbers ~ Zooplankton, crustaceans, mussels,
and aquatic insects eat algae. If water
quality is impaired and these animals are reduced in numbers, the algae may
grow in large numbers as there are fewer animals there to eat them.
These and other more complex
factors operate in combination, and no one factor can be pinpointed as a cause
of high levels of algae.
High levels of blue-green algae
blooms can persist for two to three weeks, months and even an entire summer
period if conditions are favourable.
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Blue-green Algae Special Features
There are hundreds of different types of blue-green
algae. Some types of blue-green algae have special features that other algae
just don't have. These are:
-
Buoyancy
-
Gelatinous
protection
-
Reproductive
Cells
-
Phosphorus storage
-
Nitrogen
fixation
Buoyancy ~ Some
types of blue-green algae have gas vacuoles which enable them to change their
position vertically in the water column.
They hide below the surface most of the time, only rising to the surface
in the middle of the day to get sunlight for food and growth. This is an
advantage because they can avoid predators and find areas with higher food levels.
Gelatinous Protection ~ Some blue-green algae have a jelly-like
substance which surrounds their bodies.
This helps them because blue-green algae predators are filter feeders;
when the blue-green algae get eaten only the jelly gets digested, allowing the
algae cells pass through unharmed.
Reproductive Cells ~ Some
blue-green algae have specialised reproductive cells which are larger than
normal cells and are able to reproduce sexually. This enables the algae to grow considerably
faster than normal algae. During times
of drought these cells are also able to lay dormant in the soil for years, and
are able to start reproducing quickly once water returns.
Phosphorus Storage ~ Some
blue-green algae are able to store phosphorus within their cells so that in
times of low nutrient levels they have a store available to use.
Nitrogen Fixation ~ Some
blue-green algae are able fix nitrogen directly from the air; therefore in
times of low nitrogen some blue-green algae are still able to grow when other
algae can't.
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Blue-green Algae Toxins and Symptoms
Direct skin contact with water containing
high levels of blue-green algae through showering, bathing, swimming, water
skiing and other recreational activities may result in a variety of symptoms.
The outer walls of all
blue-green algae contain toxins that are contact irritants and can cause the
following symptoms in both
humans and animals:
- Skin irritations & rashes
-
Diarrhea, vomiting or gastroenteritis
- Conjunctivitis & eye irritation
-
Asthma
-
Sore
throat
-
Hayfever-like
symptoms
People with sensitive skin,
asthma, hayfever and other allergies are more likely to be affected by the
contact irritant toxins present in all types of blue-green algae. Some people may be unaffected by the contact
irritant toxins; however, symptoms may not be immediate and can take a few days
to appear. If you experience symptoms
you should seek medical attention.
Some types of blue-green algae
are special and have additional toxins that attack the liver, kidneys and
nervous systems. These toxins will make
everyone, not just sensitive people, sick when ingested. The severity of
symptoms may be proportional to the amount of contaminated water consumed and the
particular species of blue-green algae producing the toxins.
Symptoms for these toxins
are similar for both humans and animals and include:
-
Nausea
- Vomiting
-
Abdominal
pain
-
Convulsions
-
Paralysis
-
Liver/Kidney problems
-
Constipation
-
Skin Sensitisation
-
Muscle weakness
The symptoms experienced as a result of ingesting water containing these
toxins can take up to a week to appear. If you experience symptoms you should seek
medical attention.
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Risk to Livestock and Other Animals
Livestock including cattle, sheep
and poultry may be affected as a result of drinking water contaminated with
blue-green algae.
Possible symptoms that stock may
exhibit include convulsions, paralysis, liver damage, constipation, abortion
and skin sensitivities. Milder cases of blue-green algae poisoning in stock can
cause loss of appetite, and may cause a consequent decline in milk yield in
dairy cattle. In extreme cases, stock deaths can occur following ingestion of
high concentrations of potentially toxic blue-green algae.
Dogs are particularly susceptible
as blue-green algae can attach to their coats and be swallowed during
self-cleaning.
If you suspect that your animals
are showing symptoms of contact with blue-green algae you should seek
veterinary advice.
When there are high levels of blue-green algae present it is recommended
that alternate
water supplies be utilised. Advice on the safety and suitability
of alternative sources for on-farm use may be obtained from the Department of
Primary Industries (DPI) by phoning 136 186 or visiting www.dpi.vic.gov.au.
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Risk to Irrigated Pasture
Some blue-green algae toxins will
remain toxic in a dry form. Continued application of heavily affected waters on
pastures (eg: from dairy waste recycling dams) can lead to significant toxin
build up on foliage. Although this is a rare occurrence requiring special
circumstances, this residue could potentially have similar symptoms to those
previously described.
When there are high levels of blue-green algae present it is recommended
that alternative
water supplies be utilised. Advice on the safety and suitability
of alternative sources for on-farm use may be obtained from the Department of
Primary Industries (DPI) by phoning 136 186 or visiting www.dpi.vic.gov.au .
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Risk to Edible Plants
Plants do not appear to absorb
toxins, however it is recommended that water with high levels of blue-green
algae should not come in direct contact with parts of plants that may be eaten
(ie fruit and vegetables). Before eating, vegetables and fruit should be
thoroughly washed and rinsed with water that does not contain high levels of
blue-green algae.
When there are high levels of blue-green algae present it is recommended
that alternate
water supplies be utilised. Advice on the safety and suitability
of alternative sources for on-farm use may be obtained from the Department of
Primary Industries (DPI) by phoning 136 186 or visiting www.dpi.vic.gov.au.
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Blue-green algae in Farm Dams or Private Farm Channels
If you suspect you have blue-green algae in your farm dam advice on the
management of blue-green algae blooms may be obtained from the Department of
Primary Industries (DPI) by phoning 136 186 or visiting www.dpi.vic.gov.au.
Water supplied by G-MW is not fit for any use that may involve human
consumption, either directly or indirectly, without first being properly
treated. Human consumption includes
showering, bathing, washing, cooking, ice making and drinking. Commercial systems for treating individual
household water supplies are available and can be found by looking in the
"Water Treatment and Equipment" section in the Yellow Pages.
The Department of Health has a brochure on Private Drinking Water
Supplies that G-MW recommends reading.
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Alternate Water Supplies
When there are high levels of
blue-green algae present it is recommended that you seek alternative water
supplies.
Boiling the water will not make the
water safe and may in fact increase the toxicity of the water. Boiling the
water bursts the blue-green algae cells and release toxins directly into the
water. The toxins are not able to be destroyed by boiling, therefore showering
in or drinking untreated water will be unsafe.
Water supplied by G-MW is not fit for any use that may involve human
consumption, either directly or indirectly, without first being properly
treated. Human consumption includes
showering, bathing, washing, cooking, ice making and drinking. Commercial systems for treating individual
household water supplies are available and can be found by looking in the
"Water Treatment and Equipment" section in the Yellow Pages.
The Department of Health has a brochure on Private Drinking Water
Supplies that G-MW recommends reading.
Individuals will have to
determine the best options for their particular circumstances. Options may include good quality bore water,
carted water, bottled water or tank water.
Advice on the safety of
alternative sources of drinking water supply may be obtained from local
government environmental health officers.
Advice on the safety and suitability of alternative sources for on-farm
use may be obtained from the Department of Primary Industries (DPI) by phoning
136 186 or visiting www.dpi.vic.gov.au.
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Blue-green Algae Treatment Options
At present, there are few options
for the treatment of blue-green algae affected water.
Blue-green algae are very small and therefore they cannot be removed
manually.
Urban water authorities employ
sophisticated treatment systems including expensive activated carbon treatment
to treat drinking water supplies.
Commercially available systems
for treating individual household drinking water supplies do exist, although
these are not suitable for treating the large volumes of water needed for
livestock water supply.
Commercial systems for treating individual household water supplies can
be found by looking in the "Water Treatment and Equipment" section in
the Yellow Pages.
Copper sulphates, or other copper
based products, are often promoted as algicides for use in farm dams. These products can have major ecological
impacts as they kill everything in the water, not just blue-green algae, and
should never be used in creeks, rivers or lakes. Algicides ideally need to be applied before
algae are in very large numbers and therefore don't fix the problem in the
long-term; also in the short term they can actually make the problem worse, as the
blue-green algae release toxins as they die. Specific approval from regulatory
authorities such as, but not limited to, the Environment Protection Authority (EPA) is
required for their use.
In short, treatment of water for
domestic and stock or irrigation use by individuals is likely to be
impracticable, however potential sources of information on this option are:
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