From the City of Rockwall:
Some questions have arisen lately about a blue-green algae (or cyanobacteria) bloom in ponds, lakes and streams. The questions stem from a recent incident in Austin, as well as other cities across the country, where pets died after ingesting lake water affected by the blue-green algae. We consulted with chemists at the North Texas Municipal Water District about cyanobacteria, and they offered some advice. It must be stressed that while people can get extremely ill, no harm has come to people, and drinking water is completely safe because of the treatment processes. However, there is no effective way to test or pre-warn for dangers to pets—so the best advice for pet owners is to consult a veterinarian before taking your dog to a lake, pond or stream during the hot summer months.
The danger from a blue-green algae bloom comes from the oil that may be secreted when certain types of algae bloom. Blooms typically happen during the hotter months of the year, from May through October. However, not all blue-green algae emits a toxic oil. The problem with testing lies in the fact that a test performed on one day may show no issue, and the very next day a bloom with toxic oil may be present, rendering a test both impractical and ineffective. Since it’s difficult to monitor the amount of water a dog ingests while playing in water, the best advice may be to avoid the water altogether during times when blooms are most likely.
The toxic oil creates a unique taste and odor, and yet those are not always clear indications of toxicity. It’s important to remember that the treatment process for drinking water is robust and produces a good barrier for toxicity—with a thorough process that includes a combination of ozonation, filtration and disinfection. Talk to your veterinarian and develop the best plan for you to keep your dogs safe.