Harmful Algal Blooms: When It Isn’t Good to Be Green

Interview with Ben Holcomb

If you’ve ever recreated at one of Utah’s lakes or reservoirs, you’ve probably seen areas where greenish scum was floating on the water or collecting on the shore. What you probably didn’t know — at least until this past week with the closure of Utah Lake — was that this bright-green water is a sign of a harmful algal bloom. These blooms are caused by a rapid increase in an organism called cyanobacteria that can produce toxins that are harmful to humans, pets, wildlife, and fish.

Excess nutrients in waterbodies, particularly phosphorus, can trigger algal blooms. Discharges from wastewater treatment plants, runoff from agricultural operations, and stormwater runoff can carry nitrogen and phosphorus into waterways and promote the growth of cyanobacteria.

We interviewed Ben Holcomb, the Biological Assessment and Harmful Algal Bloom (HAB) Programs Coordinator for the Division of Water Quality (DWQ), to learn more about cyanobacteria, what causes harmful algal blooms, and how DWQ is addressing this growing problem in the state.

What are cyanobacteria?

Cyanobacteria, also known as blue-green algae, aren’t actually algae. They are prokaryotes, single-celled aquatic organisms that are closely related to bacteria and can photosynthesize like algae. These microorganisms have been a natural part of aquatic ecosystems for thousands of years — perhaps the organisms to first produce oxygen on Earth. Under the right conditions, however, their populations can explode to create large blooms. They multiply when elevated levels of nutrients (nitrogen and phosphorus), warm temperatures, and calm water combine to create the perfect environment for rapid growth. Although many algal blooms are not toxic, especially the green algae, some types of cyanobacteria produce nerve or liver toxins. When this occurs, the event is known as a Harmful Algal Bloom (HAB).

Can you tell us more about the toxins produced during an algal bloom?

These poisons, called cyanotoxins, are produced naturally inside the cells of certain species of cyanobacteria. When the cells lyse (break open), the toxins may be released. In many species, the toxins remain within the cells while the bloom is growing and are only released into the water when cells die or rupture. Other species release the toxins during both their growth period and cell death. Some of these toxins attack the liver (hepatotoxins), others target the nervous system (neurotoxins), while still others irritate the skin (dermatoxins).

How can somebody tell if a lake or stream is experiencing a harmful algal bloom?

Cyanobacteria can appear as single cells, filaments of cells, or colonies. Their characteristic pigment (“cyan”) gives them their blue-green color, although they can also appear as blue, green, red, or brown in the water. They may look like parallel green streaks, blue, white or green spilled paint, green dots or clumps on the surface, or bright green or “pea-soup” colored water. It can be hard to tell a HAB from other non-toxic algal blooms, and sometimes several types of algae can be present at one time in a bloom.

How do you know whether a bloom is toxic or not?

Unfortunately, you can’t tell if a bloom is toxic just by looking at it. Some of the samples from Utah Lake containing the highest cell counts were in areas that did not appear green on the surface. Because cyanobacteria can also sink and float in response to changing conditions, blooms that may not be apparent at the surface may still be present in the lake. In addition, there are forms of cyanobacteria that grow on the bottom of rather clear lakes. So, even perfectly clear lakes may harbor toxin-producing cyanobacteria in large numbers.

While toxin tests can help confirm the presence of toxins, health and environmental agencies rely primarily on cell counts as the best method for determining risk to human and animal health from a bloom. Cell counts are much quicker, consistent and repeatable compared to evaluating fickle toxins. In addition, cell counts provide a better linkage to human health symptoms than toxins by themselves. We may only know a handful of the toxins that cyanobacteria produce.

What is the Division of Water Quality doing to prevent harmful algal blooms?

While we have little control over some of the conditions that promote algal blooms — high air and water temperatures, low water levels, sunlight, and calm waters — we can do something about excess nutrient levels. DWQ has spent the past five years working on a nutrient reduction strategy to identify appropriate thresholds while considering the additional excess nutrient impacts from a growing state population.

For instance, we estimate that 80 percent of the phosphorus in Utah Lake comes from wasterwater treatment plants. Other waterbodies with frequent algal blooms, such as Farmington Bay, are also adversely affected by wastewater discharges. Our Water Quality Board voted last year to apply a technology-based standard for phosphorus discharges from wasterwater treatment plants that will significantly reduce the levels of nutrients entering many of Utah’s lakes and streams. Nitrogen and ammonia limits are likely to follow soon.

Do you have plans to predict when harmful algal blooms may occur on Utah’s waterbodies?

The ability for our office to predict blooms would help us tremendously, making it possible to warn the public about blooms and using our resources efficiently. DWQ recently received funds to purchase high-frequency water quality instruments for deployment at a few high-risk waterbodies. The data collected will be modeled after an effort in Ohio and Florida that uses a combination of water quality, remote sensing, and meteorological data. Ohio operates on a five-day forecast to predict cyanobacterial blooms. Currently, we can’t even predict the correct month.

Our predictions could improve with increased satellite coverage. Right now, our area receives satellite images about once a week at best. After this year, we are expecting coverage every two to three days. When these data become available and linked with our water quality and meteorological information, we should have a tremendous predictive tool for our most high-risk waterbodies.

Do you have any plans to help reduce algal blooms on Utah Lake?

DWQ is prioritizing resources to study Utah Lake over the next few years. Not only are we assembling our sister natural resource agencies, but we are partnering with every University on the Wasatch Front for this effort. We have also made development of site-specific nutrient standards a priority for Utah Lake and are in the early stages of a workplan that will help us ensure that agricultural, recreational and aquatic life uses are protected on Utah Lake and downstream.

Want to know more? Check out our harmful algal bloom webpages for more information. You can visit our Utah Lake algal bloom webpage for up-to-date information about the ongoing bloom in Utah Lake and the Jordan River.

I am the Division of Water Quality (DWQ) coordinator for the biological assessment and harmful algal bloom programs. I’ve worked at DWQ for seven years and my past work includes salmon, water quality, and tribal sovereignty in the Pacific Northwest.