If you think your tap water smells strange today, you're not alone.

South and Central Austin residents began noticing the unusual smell Thursday morning. Austin Water initially said work on a waterline was to blame, but in an afternoon update, the utility said it was likely caused by the presence of zebra mussels in a raw water pipeline.

The line is at the Ullrich Water Treatment Plant just southwest of Lake Austin, which had become infested with zebra mussels about a year ago. It had been turned off for two weeks, but returned to service Wednesday.

There is no threat to the water and it's safe for customers to drink, Austin Water spokesperson Ginny Guerrero said.

Sounds like Zebra Mussels were responsible for the nasty smelling tap water in South Austin this morning. Want a refresher on one of Austin's newest invasive species? Here's some of my recent(ish) reporting. 1/6 — Mose Buchele (@MoseBuchele) February 7, 2019

Austin Water said it is adding "powdered activated carbon" to help with the odor. It is also flushing water lines in the affected areas.

The utility says it expects the issue to be resolved in the next 24 hours.

This story has been updated.