Some algae can be harmful to humans and animals, and Austin Water has regularly monitored both raw source water, as well as treated drinking water for the presence of cyanobacteria and cyanotoxins since 2015. Austin Water conducts routine testing for the presence of cyanotoxins in both raw lake water taken from Lake Austin and Lake Travis, as well as in water that has finished the treatment process at the Handcox, Davis, and Ullrich Treatment Plants. Tests for the presence of phytoplankton (microscopic algae) and cyanotoxins in raw lake water are conducted on a weekly basis. The sampling frequency may be adjusted based on changing conditions. Current tests are non-detect for cyanotoxins in raw or treated drinking water.

In addition, Austin Water is investing in leading-edge technology to shorten the time between sampling and test results to protect public health and safety. We plan to use digital imaging particle analysis to detect harmful algae, as well as same day testing instruments in our own lab. We are working to have these  instruments in place by the end of the year. We also meet regularly with our counterparts at the City of Austin’s Watershed Protection Department and the Lower Colorado River Authority to review and report on our respective testing and mitigation approaches.

Austin’s drinking water meets all state and federal standards. The Environmental Protection Agency has no set regulatory limits for cyanotoxins in drinking water. However, Austin Water is committed to monitoring for the lowest threshold levels set for two cyanotoxins in EPA Health Advisories. We are committed to providing safe and healthy drinking water to our community. If at any time there is an issue with your drinking water, Austin Water will notify you as soon as possible.

The Frequently Asked Questions and responses below provides information about naturally occurring cyanobacterial algae blooms and how Austin Water is working to protect public health and safety by providing high-quality water services.

 

FAQs About Harmful Cyanobacterial Algal Blooms & Drinking Water
 

What are cyanobacteria?

Cyanobacteria, also called blue-green algae, are microscopic organisms found naturally in all types of water. These organisms use sunlight to make their own food. In warm, nutrient-rich waters, cyanobacteria can multiply quickly, creating algal blooms that spread across the water’s surface.

Two types of harmful algal blooms are planktonic and benthic proliferations. Planktonic are free-floating microscopic cells that are suspended in the water column or float as scum on the water surface. Benthic algae originate on the bottom of lakes in shallow water. Benthic mats can remain on the bottom of the lake or float to the surface. Austin Water monitors the water entering our treatment plants for both types of harmful algae.

 

How are cyanobacterial algal blooms formed?

Cyanobacterial blooms form when cyanobacteria start to multiply very quickly. Blooms can form in warm, slow-moving waters that are rich in nutrients from sources such as fertilizer runoff or septic tank overflows. Cyanobacterial blooms generally need an abundance of nutrients to grow. The blooms can form at any time, but most often form in late summer or early fall. Algal blooms and cyanobacteria are monitored closely by Austin Water’s Water Quality Lab, as well as the City of Austin’s Watershed Protection Department and the Lower Colorado River Authority.

 

Why are some cyanobacterial algal blooms harmful?

Harmful cyanobacterial algal blooms may affect people, animals, or the environment in the following ways:

  • Some cyanobacteria in algal blooms may produce toxins called cyanotoxins that can make people and their pets sick. Those experiencing symptoms should consult a physician right away.
  • The blooms can block or reduce the sunlight that other organisms need to live.
  • They use up nutrients that other organisms need to live.
  • They use up the oxygen in the water as they die down, which can kill fish and other aquatic life.
 

How do cyanotoxins affect drinking water quality?

Cyanobacterial algal blooms that create cyanotoxins can occur Lake Austin and Lake Travis, which supply drinking water for Austin. Winds and water currents can transport algal blooms near drinking water intakes at water treatment plants. If cyanotoxins enter the drinking water treatment plant and are not removed during treatment, people can be exposed to cyanotoxins through their tap water. Cyanobacteria may produce taste and odor compounds that could cause problems in drinking water.

 

Is there testing for algae and cyanotoxins in water?

There are no national or state requirements for monitoring cyanotoxins. While algal blooms may contain cyanobacteria that have the potential to release cyanotoxins, these harmful toxins may not actually be present in the water itself.

Austin Water conducts routine testing for the presence of cyanotoxins in both raw lake water taken from Lake Austin and Lake Travis, as well as in water that has finished the treatment process at the Handcox, Davis, and Ullrich Treatment Plants. Tests for the presence of phytoplankton (microscopic algae) and cyanotoxins in raw lake water are conducted on a weekly basis. The sampling frequency may be adjusted based on changing conditions. Current tests are non-detect for cyanotoxins in raw or treated drinking water.

Additionally, Austin Water uses several processes in our treatment plants which are effective in removing cyanobacteria and cyanotoxins. The harmful cells containing the toxins can be physically removed through the coagulation, flocculation, sedimentation, and filtration process. Chlorine, which is part of the plant’s disinfection process, is destructive to cyanotoxins. Finally, the powdered activated carbon that is used to remove taste and odor causing compounds also removes cyanotoxins.

 

How can I help reduce cyanobacterial harmful algal blooms from forming?

Reducing nutrient pollution, such as excess nitrogen and phosphorus, is essential to reducing the formation of cyanobacterial blooms. Excess nutrients may originate from agricultural, industrial, and urban sources as well as from atmospheric deposition. Things you can do to reduce nutrients in your local waterways include:

  • Use only the recommended amounts of fertilizers on your yard and gardens to reduce the amount that runs off into the environment.
  • Properly maintain your household septic system.
  • Maintain a buffer of natural vegetation around ponds and lakes to filter incoming water.
    • Stop fertilizing within 20 feet of lakes, rivers, and ponds.
    • Plant natural vegetation around ponds and lakes to filter incoming water.
  • Do not add fertilizers when the ground is frozen.
  • Do not apply fertilizer immediately before or during rain and snow.
 

For more information on cyanobacterial blooms and cyanotoxins, please visit:

www.cdc.gov/habs

http://www.epa.gov/cyanohabs

https://www.epa.gov/ground-water-and-drinking-water/ cyanotoxins-drinking-water.