An overnight spike in silt in Austin's tap water triggered an official boil-water notice from state regulators.
The water briefly exceeded the Texas Commission on Environmental Quality’s regulatory standards for drinking water quality, surpassing a limit of 5 turbidity units. The city's earlier boil-water notice was only precautionary.
Turbidity refers to the cloudiness of water. It's a measurement used to reflect the amount of contaminants present, such as silt, mud and debris. Turbidity itself has no negative health effects, but high levels of it can create an environment where bacteria grows.
Austin Water officials said the spike lasted only a short time and turbidity levels are back to the same levels the utility saw yesterday afternoon.
“This spike in turbidity does not require any change [and] does not put the public in any additional risk,” Austin Water Public Information Officer Ginny Guerrero said. “We’re still asking folks to boil their water but that brief moment that the turbidity got a little worse for us last night triggered this additional notification.”
Austin’s drinking water is usually well below the state standard level of 0.3 turbidity units. The current level is hovering around 1.
"At higher outputs ... water's moving through the [water-treatment] plant faster, and water quality starts to break down," Austin Water Director Greg Meszaros said at a news conference this afternoon. "Our systems just cannot treat this really nasty raw water."
Austin officials issued a boil-water notice Monday after historic flooding in the Llano River made its way to the Colorado River and overwhelmed the city's water-treatment plants.
"The Llano River flooding ... washed untold amounts of debris, silt and other products downstream," Meszaros said. "This is a natural disaster. It's like a water-quality bomb went off in the river."
He said all the city's water-treatment plants were operating at "significantly impaired capacity," but that the Ullrich plant, which serves most of the area south of the river, was struggling the most.
In order for the boil-water order to be lifted, Meszaros said, the river would need to stay stable, plant capacity would need to be above demand, and the water would need to test clean in a variety of tests.
Right now, production is outpacing demand, Meszaros said, so the message is to continue to conserve water.
"We can't control the rain, but we can certainly have our community try to control its water use, and that will help us replenish our reservoirs," he said. "It will help us if we have another event where we have to shut down a plant to clean it or stabilize it."
Thank you, Austin! This graph shows how you are responding to our request to reduce your water use. Please keep it up while our water treatment plants recover and continue to provide the city’s basic needs. pic.twitter.com/5zK9mnXFji
— Austin Water (@AustinWater) October 24, 2018
KUT's DaLyah Jones contributed to this report.
This post has been updated.