Blue-Green Algae Returns to Red Bud Isle, Walsh Boat Ramp

Austin Watershed Protection staff have observed thick mats of blue-green algae, some of which may be toxic, notably near Red Bud Isle on Lady Bird Lake and at Walsh Boat Landing on Lake Austin. Samples were collected at all six monitoring sites on the lakes for testing. At this time of year, blue-green algae mats may be present in other parts of either lake and our creeks. Community members should be cautious and avoid contact with algae. They should keep dogs away from water with algae mats.

The mats usually look like dark blobs floating on the surface and can be mixes of different kinds of algae. They may be mixed in with aquatic vegetation. As the weather continues to heat up, conditions for algae will become more favorable, and we expect to see more in our waterways. 

Assess Before You Enter Waterways

If any of the following conditions are present, stay out of the water. They could indicate reduced water quality.

• Algae along the shoreline

• Stagnant, warm or murky water

• Scum or surface film.

In addition, do not enter the water if there has been rain in the past three days.

After Entering the Water

• Do not drink water directly from natural water bodies.

• Avoid contact with algae.

• Rinse skin, hair, and animal fur thoroughly after contact with water.

• Do not allow pets to lick their fur before rinsing them off.

If you or your pet experiences sudden, unexplained illness after swimming, contact your medical provider or veterinarian immediately. Residents are encouraged to report suspected human or animal illnesses related to algae using the City’s online reporting form.

The mats of blue-green algae present at Red Bud Isle are similar in appearance to conditions in May and June in previous years. For the past five years, we have applied lanthanum-modified clay to manage sediment phosphorus in an effort to reduce the growth of algae as part of a $1.5 million pilot program. This year is a control year with no application so we can evaluate the effectiveness of the pilot program and whether it is beneficial to continue investing public funds at the previous level. 

Algae is not the only risk when spending time on Austin’s waterways. Natural water bodies can contain algae, bacteria, parasites, and other hazards. Austin Watershed Protection monitors the water quality in our lakes and creeks to understand how the urban environment affects our water bodies and to develop effective policies to protect them. We do not regularly test water in our creeks and lakes for recreational use. 

About Austin Watershed Protection

Austin Watershed Protection protects lives, property, and the environment of our community by reducing the impact of flooding, erosion, and water pollution. Visit AustinTexas.gov/Watershed to learn more.