A toxic threat to Lady Bird Lake has been dramatically reversed, according to a new government report announced Monday.
The popularity of Lady Bird Lake can be counted by the number of people on the water. But the quality of the water that has been measured by core samples like this one.
"It’s the evidence that is needed to justify the ban on coal tar across the country,” said U.S. Congressman Lloyd Doggett.
The Austin Democrat’s call for change was joined by Austin mayor Lee Leffingwell, who was part of the local effort that started in 2005.
"And PAH's were discovered in Barton Springs Pool and you know when something like that happens it does create a stir,” said Mayor Leffingwell.
Polycyclic aromatic hydrocarbons come from coal-tar based pavement sealant. Eight years after the city banned the product, a government survey team measured how much of the toxic substance can still be found in the muddy lake bottom.
"We saw something that surprised us,” said lead scientist for the U.S. Geological Survey study, Peter Van Metre.
That surprise was a nearly 60 percent reduction, dramatically reversing a 40 year trend. Van Metre said he is confident the reduction is directly linked to the ban.
"Yes, because we did look pretty hard at vehicle sources, and it’s really clear the big drop is a drop of inputs from coal tar sealant coating," said Van Metre.
Reducing the toxicity of the lake sediment adds to the overall improvement to the water quality. It is not only safe to get into the water; officials say you can also eat the fish.
There is another threat to the water quality here and while it is also linked to runoff, it cannot be addressed with a ban.
City Stream Ecologist, Mateo Scoggins, says fertilizers from residential and commercial properties can trigger algae blooms.
"We're worried about that because that can change the character of Lady Bird Lake," said Scoggins.
Prevention has been difficult because the city does not have the authority to prohibit the use of weed and fee products. Going organic is encouraged.
"That’s a hard choice you’re asking folks to make. That’s true, we're asking people to think a little harder and look a little farther, for a better solutions to these problems,” said Scoggins.
"So let’s get to work," said Representative Doggett, who has yet to find a Republican Co-Sponsor for his legislation.
Despite that, the Congressman says he will continuing to push his legislation for a national ban on coal tar sealant, but will also work to get more communities to pass their own bans.