A duck glides between dwindling patches of algae. Steve Bloom The Olympian
A duck glides between dwindling patches of algae. Steve Bloom The Olympian


Dr. Wood: How algae in lake water can make you sick

By Dr. Rachel Wood

Contributing writer

June 24, 2017 09:00 AM

Summertime brings warmer weather, but the change in weather doesn’t just mean more beach days, yard work, and swimming. It can also mean an increase in algae blooms, both in lakes and along shorelines.

Not all algae blooms are bad for your health, but they all effect the quality of water in and around Thurston County.

There are lots of different kinds of algae, but generally, when you hear about an algae bloom in a Thurston County lake, or along a shoreline, it’s actually a kind of bacteria. Cyanobacteria (also known as blue-green algae) is a bacteria that can photosynthesize light into food just like plants.

Algae blooms are being studied all over the world, but there is still relatively little known about what causes algae blooms to form and produce toxin. What we do know is that water temperature, nutrients (especially phosphorus and nitrogen), sunlight, wind, and rain affect algae blooms. We know that blooms can present health and safety risks to people and animals, so when a bloom is present, we advise people and pets to stay out of the water, whether at a lake or on the beach.

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Recent closures at Summit Lake in Thurston County have put a spotlight on the dangers of toxic algae blooms, especially when the water serves as the primary drinking water source.

While science hasn’t yet determined what makes an algae bloom become toxic, it’s important to note that there are a variety of toxins that are problematic to human health. Anatoxin-a (the toxin released by the algae at Summit Lake) is a powerful neurotoxin and can cause severe symptoms and even death. Microcystin is another, more common liver toxin that accumulates over a lifetime.

Because these toxins can have serious impacts on people, and because any toxin will naturally circulate in water, it’s not uncommon for lakes or beaches to have advisory signs posted, warning people to avoid water contact when a toxic bloom is located.

What can you do to protect yourself from risks posed by algae blooms?

▪ Stay informed. Check to see if a bloom is present before you go out to the lake. For Thurston County lakes, you can visit our web site. The Washington State Department of Health has great information on toxic algae blooms.

▪ When in doubt, stay out! Don’t risk yourself or your family by swimming or recreating in water with algae blooms. And keep pets and animals out too.

▪ Catch and release. If you fish in a lake with a bloom, catch and release is the best way to reduce risk to you and your family.

There are things our community can do to reduce the nutrients that feed algae blooms.

Maintain or restore native plants around lake shorelines and streams that feed the lake. Native wetland plants help filter water and do not require pesticides or fertilizers for maintenance.

Be cautious with lawn and plant fertilizers and pesticides. Do not over water, over fertilize, or use more than the recommended amount of pesticides.

Use proper care and maintain your septic system. Damaged septic systems are a source of nutrients into nearby water. Inspect your system annually and pump when needed, typically every 3-5 years.

Prevent water runoff from agricultural and livestock areas. Do not allow livestock to drink or defecate in streams or lakes. Do not feed waterfowl.

Take steps to prevent erosion around construction and logging operations. Erosion can carry nutrient-rich soil into nearby lakes.

To learn more about toxic algae blooms across Washington state, visit the Washington State Toxic Algae website, www.nwtoxicalgae.org.

Reach Dr. Rachel C. Wood, health officer for Thurston and Lewis counties, at 360-867-2501, woodr@co.thurston.wa.us, or @ThurstonHealth on Twitter.