Toxic Algae in Spanaway and Ohop Lakes

Many people spotted Spanaway Lake being treated with Phoslock^® on Tuesday, August 20. It is made from bentonite clay. When applied to water, the lanthanum reacts with phosphate to create an inert mineral called rhabdophane, which is insoluble and non-toxic. This reaction permanently binds the phosphorus in the water, and can also lock up phosphorus in the bottom sediments of lakes and ponds.

Phoslock is safe for use in aquatic environments and doesn’t harm fish, macroinvertebrates, or other wildlife. It can help prevent problems like algae growth and aquatic ecosystem disruption that can be caused by high levels of phosphorus.

From the Tacoma Pierce County Health Department:

People and pets should avoid areas of the lakes with visible algae.

On Thursday, August 15, we issued toxic algae caution advisories for Spanaway Lake and Ohop Lake. You should avoid areas of the lakes where you see algae because they can pose health concerns. You’ll see signs posted at the lakes to let you know about the advisory.

When you see algae, don’t swim, wade, waterski, or fish. Keep in mind as wind direction changes, the algae could move elsewhere in the lake. When in doubt, stay out!

We sampled the lakes on August 12 and 13 and received results on August 15. We will inspect the lakes again next week. If the bloom is gone, we will leave the advisory in place for 2 weeks out of an abundance of caution. Find our list of current surface water advisories at tpchd.org/advisories.

What are toxic algae?

Toxic algae, also known as cyanobacteria, occur naturally in lakes. They can produce toxins that make people, pets, and animals sick. Read our brochure to learn more about toxic algae.

How can you spot toxic algae?

Toxic algae can form a scum layer and look like green pea soup. They can also look streaky, be dispersed in the water column, or form clumps. Algae can have different colors, most often green but also brown, red, and blueish. Wind and weather conditions can change the amount and location of algae.

What are the symptoms?

Muscle weakness.
Vomiting.
Diarrhea.
Nausea.

See your medical provider if you may have been in water with toxic algae and have any of these symptoms. Small children are at most risk since they have small bodies and are likely to ingest water.

Skin in contact with toxic algae can become irritated or break out in a rash. This is different from Swimmer’s Itch.

How can toxic algae affect my pets?

Pets are at great risk. They have small bodies and are more likely to ingest larger amounts of toxic algae. They may drink water with toxic algae and lick their fur. Take your pet to the vet when it shows any of these symptoms.

Lethargy.
Vomiting.
Diarrhea.
Convulsions.
Difficulty breathing.
General weakness.

What should I do if exposed to toxic algae?

You can get sick within minutes to hours of exposure. Rinse off anyone or any pets exposed to toxic algae immediately. Look for signs of illness and seek medical treatment if symptoms occur. For exposed pets, keep them from licking their fur to groom.