Frequently Asked Questions
Safety Precautions
How can you protect yourself, your family, and your pets from exposure to HABs?
- Don't swim, water ski, or boat in areas where the water is discolored or where you see foam, scum, or mats of algae on the water.
- If you do swim in water that might have a HAB, rinse off with fresh water as soon as possible.
- Don't let pets or livestock swim in or drink from areas where the water is discolored or where you can see foam, scum, or mats of algae in the water.
- If pets (especially dogs) swim in scummy water, rinse them off immediately - do not let them lick the algae (and toxins) off their fur.
- Don't irrigate lawns or golf courses with pond water that looks scummy or smells bad.
- Report any musty smell or taste in your drinking water to your local water utility.
- Respect any water body closures announced by local public health authorities.
Is it safe for livestock to drink water with blue-green algae in it? - No. An alternative safe drinking supply must be found until the water supply is declared safe. Most livestock will prefer not to drink the water if an alternative supply is available.
Are all animals affected the same? - Most important is the amount of exposure to the toxins. Some animals are particularly sensitive. Dogs have sensitive noses and lick their fur to clean themselves, possibly taking in concentrated algae. Fish and water birds appear to be little affected. Most livestock will avoid contaminated water, if possible, but where they are forced to drink through scum (for example where a fence forces them to the leeward side of a dam) they may die.
Can livestock pick up toxins from irrigated pasture? - Yes. Some of the blue-green algal toxins will remain toxic in dry form. Continued application of heavily affected waters (say 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 can affect livestock.
Is blue-green algae affected water safe to drink after it has been boiled or filtered? - NO. The water needs to be filtered through activated carbon to remove any toxins. Toxins will not be removed by boiling, normal water filter systems or adding household disinfectant.
Can I cook with water with blue-green algae in it? - NO. Remember boiling does not remove toxins from the water.
Can I wash clothes and dishes in water with blue-green algae in it? - Where possible use alternative water supplies. If you are unable to find another water source, take the following precautions:
- Use rubber gloves when handling wet washing or dishes.
- Rinse dishes with uncontaminated water.
- Remove surplus water with a dish towel.
- If possible, give the laundry a final rinse with uncontaminated water. Sun dry the clothes and air them for a few days.
Can I water fruit and vegetables with contaminated water? - Yes. These do not appear to take up the toxins. However, avoid fruit and vegetables coming in contact with the contaminated water. Make sure you wash the fruit and vegetables in clean water before eating.
Can I eat fish or shellfish caught in water with blue-green algae in it? - You should not eat shellfish as they can concentrate toxins. The liver and gut of fish are also likely to be toxic. Other parts of the fish may be eaten but they must be well cleaned. Further studies need to be done on the build-up of toxins in fish.
Is it safe to swim in water with blue-green algae in it? - Generally no. This will depend on the numbers and type(s) of algae present. At even low levels of some blue-green algae people and animals with sensitive skin may show some allergic reactions to the toxins present in the water. Not all people are sensitive to blue-green algae allergens and for those who are the effect increases with increased exposure. The more concentrated the algae and the longer people remain in the water the more severe the symptoms.
Is it safe to boat or canoe in water where there is an algal bloom? - Safety will depend on the level of the blue-green algae. Always avoid skin contact with the water. Not all people are sensitive to blue-green allergens and for those who are, the effect increases with increased exposure. The more concentrated the algae and the longer people remain in the water the more severe the symptoms.
Will wearing a wetsuit protect me from algal toxins? - No. In fact wetsuits may concentrate algae at the collar and cuff areas and rub cells against the skin. This may cause a particularly strong skin reaction at the points where water enters the suit. Be careful to rinse algae off the suit with fresh water if you have used it where algae concentrations are high.
Will blue-green algae affect my irrigated crops? - Not directly in relation to toxins. The crops are not known to take up the toxins. However, blue-green algae are fast growing and can shade and foul rice crops if they occur in bays before the crop established a cover above water level. This can cause significant yield loss.
When blue-green algae is present should I pump water from a greater depth? - Water in deep dams may form layers of different temperature. If there is no alternative water supply using water form areas not covered by scums or from deeper (notably cooler) layers in dams MAY reduce algal exposure and risks.
Is the water safe once it appears to no longer have a bloom on it? - No. Blue-green algal cells lave gas bubbles in them which affect how they float. It is common for blooms to rise to the surface in calm light conditions and sink down at other times becoming much less evident from the bank. When cells die and break up it can take days for nerve toxins to disintegrate and weeks for liver toxins to disappear. It is best to wait a couple of weeks after a scum forming bloom has gone before using the water
How to treat people or animals that have been exposed to cyanobacterial
toxins? -
Get medical treatment right away if you think you, your pet, or your livestock might have been
poisoned by cyanobacterial toxins. Remove people from exposure and give them supportive treatment.
National Poison Control Hotline Number: 1-800-222-1222.
