Toxic Algae (Cyanobacteria)
Current Toxic Algae and Surface Water Advisories
Toxic Algae at Lake Tapps Possibly Linked to Human IllnessesTacoma-Pierce County Health Department received calls beginning Aug. 16 about a number of people reporting illnesses after swimming in Lake Tapps. Following an inspection of the lake, Health Department staff detected a toxic algae bloom. On Aug. 18 we issued a warning advisory, urging people and pets to stay out of the water. We received water test results Aug. 19 that showed no detectable concentrations of toxins. We then lowered the advisory to a caution, meaning people and their pets can enjoy the water but should avoid areas of algae.
The Health Department is investigating the potential link between the toxic algae bloom and the symptoms people reported, but there is no definitive laboratory test for toxic algae illness. The illnesses occurred in people ages two to 48 years, all of whom recovered within a few days.
Toxic algae, also known as cyanobacteria or blue-green algae,
can produce toxins. These toxins may kill pets, waterfowl, and other
animals. They can also cause serious illness or even death in people.
Toxic algae are naturally occurring and could have increased in number
because of impacts from human activities.
What Is A Toxic Algae Bloom?
Toxic algae can reproduce rapidly in fresh water when the amount of sunlight, temperature and nutrients are sufficient. Within a few days a "clear" lake, pond or ditch can become discolored with algae growth. A bloom forms when a sudden increase in the concentration of algae cells happens in a certain area of water. Toxic algae blooms often float to the surface and can form a surface scum. This scum, or heavy concentration of algae, can look like green paint and be several inches thick near the shoreline (click here for an example). Wind and weather conditions can greatly change the amount and location of algae.
What are the symptoms?
If someone swallows water with toxic algae, they may
- Muscle weakness.
If you know or believe someone may have swallowed water containing large amounts of algae, it is extremely important to seek medical attention.
Skin contact with toxic algae can cause irritation or a rash. This is a different rash then that caused by Swimmer's Itch.
How can toxic algae affect my pets?
The risk to pets is much greater than it is to people. Pets
have smaller body sizes, are more likely to drink water containing a
large amount of algae, and may groom by licking their fur after
contact with water containing toxic algae. Pets and other animals may
show these symptoms if they ingest toxic algae:
- Difficulty breathing.
- General weakness.
What you should I do if I’m exposed to toxic algae?
The onset of illness can happen within minutes to hours of
exposure. You should rinse off anyone or any pets exposed to toxic
algae immediately. Monitor for signs of illness and seek medical
treatment if symptoms occur. For exposed pets, keep them from licking
their fur to groom.
Can I eat fish from toxic algae contaminated water?
Avoid eating fish from areas with visible algae. Always clean
fish well and discard guts.
What should I do if I see an algae bloom?
Follow these steps to keep yourself, your family, and your pets safe:
- Do not drink lake water.
- Do not swim or water ski in areas with visible algae (looks like paint
on the surface).
- Keep pets and livestock away.
- If the area is open to the public and isn’t already posted with a Health Department sign, please call us at (253) 798-6470.
What can I do about it?
Algae need nutrients—like phosphorous and
nitrogen—to grow. These nutrients are found in animal and
human waste (sewage) and fertilizers. Here’s what you can do
to prevent toxic algae:
- Eliminate or reduce use of fertilizers.
- Properly use and maintain your septic system. Have your system inspected every one to three years and pumped as needed. For more information, visit www.tpchd.org/septic.
- Keep animal waste out of streams or lakes! Pick up after your pets, don’t feed waterfowl, and keep livestock away from the water.
- Plant native plants between your yard and the creek or lake to reduce runoff and prevent erosion.
Find out more!
- Ecology’s Fresh Water Algae Control Program: www.ecy.wa.gov/programs/wq/plants/algae/
- Human health and toxic blooms: www.doh.wa.gov/ehp/algae
- Local advisories concerning toxic blooms: www.tpchd.org/surfacewater
- Find out how to keep water clean at www.piercecountywa.org/pssh
Toxic Algae Advisory Explanations
- Caution Advisory (Posted Sign): Lake may be unsafe for people and pets.
- Warning Advisory (Posted Sign): Lake is unsafe for people and pets.
For more information, or to report a suspected algae bloom,
please call the Health Department at (253)
798-6470 or email us at EHSurfaceWater/Shellfish@tpchd.org.
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