The City of Austin has detected low levels of dihydroanatoxin in an algae sample taken in mid-March from Lake Austin near Mansfield Dam. Trace levels were also detected in two algae samples from Lady Bird Lake. Dihydroanatoxin is the same toxin that LCRA has detected in other Highland Lakes earlier this year and the same one found in 2019 and 2020 in Lady Bird Lake. Although levels of the toxin are low, they indicate an increased risk for dogs in the water bodies.
Cyanobacteria, or blue-green algae, are the source of the toxin. This type of algae can be found in waterways in Central Texas throughout the year. The algae are more prevalent in warmer, more stagnant water, and are more likely to produce toxins under these conditions. Dogs appear particularly vulnerable to dihydroanatoxin in algae mats.
Given that the toxin has been detected during the cooler season and in at least four lakes, the Watershed Protection Department plans to reevaluate its monitoring program. At this time, we are recommending that dog owners not allow their dogs to ingest or touch algae in any area lakes, creeks or water bodies. If owners allow their dogs in the water, it is at their own risk. It may help to rinse dogs after contact with water bodies to help prevent them from licking algae off their fur.
Dog owners should take their pets to a veterinarian immediately if their dogs become sick after swimming in Lady Bird Lake. Please also report the illness to 3-1-1. Symptoms of exposure may include:
- Excessive drooling, vomiting and diarrhea
- Foaming at the mouth
- Jaundice and hepatomegaly
- Blood in urine or dark urine
- Loss of appetite
- Photosensitization in recovering animals
- Abdominal tenderness
- Progression of muscle twitches
- Respiratory paralysis
At this time, the risk to humans appears low and people may continue to boat and fish, following COVID-19 safety measures. However, people should avoid handling algae. Swimming has been banned in Lady Bird Lake since 1964.