How Austin's leaky pipes are helping trees at University of Texas

In drought times, as much as half the water flowing through a creek at the University of Texas is from leaky city pipes, per a new report by UT researchers.

Why it matters: Beyond a commentary on failing infrastructure, the researchers say those broken pipes come with a silver lining — sustaining trees growing along Waller Creek, allowing them to thrive during drought conditions that take a toll on trees growing along streams in rural areas.

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Threat level: While recent rains have eased dry conditions in much of the state, most of Travis County west of I-35 is currently facing some level of drought, per the U.S. Drought Monitor .

• The Austin area has an above normal chance of rain over the next two weeks, but a long, hot summer is looming.

Stunning stat: Austin city pipes lost over 6.9 billion gallons of drinkable water in 2022, enough to fill an Olympic-size swimming pool every hour of every day that year, KXAN reported .

• Those losses cost the city more than $12 million that year, per state data.
• With more than 3,800 miles of water mains and more than 2,900 miles of wastewater pipes, the city is constantly replacing lines big and small all around Austin.

How it works: Researchers compared the growth history of bald cypress trees along Waller Creek on UT campus and along Onion Creek, at McKinney Falls State Park and the Onion Creek Soccer Complex in southeast Austin, more rural areas about a dozen miles from campus, to the drought record of the region.

• A tree's growth is recorded in rings in its wood, with thicker rings reflecting wetter times and strong growth and thinner rings reflecting drier times and little growth.
• UT professor Jay Banner, director of the university's Environmental Science Institute, and his students extracted this record from living trees by taking cores — narrow rods of wood pulled from tree trunks — and sending them to the Laboratory of Tree-Ring Research at the University of Arizona for analysis.

A view of Waller Creek at UT. Photo: Courtesy of the University of Texas at Austin Jackson School of Geosciences.

What they found: An analysis of the trees along Waller Creek revealed they were sheltered from drought, with tree growth showing only a weak connection to drought severity.

• Even during the state's most severe drought on record, which spanned most of the 1950s, the Waller Creek trees showed only a small decline in growth. In contrast, the trees of Onion Creek faced a steep decline.

What they're saying: "That's kind of what we expect in an urban environment," Banner said. "We would expect the natural system to be, well, for lack of a better term, messed up."

By the way: Earlier this year Banner received a top national teaching award .

The big picture: "Central Texas faces particularly synergistic challenges of a rapidly growing urban population and a projected increasingly drought-prone climate," Banner and other researchers wrote in a paper that appeared earlier this year in the Nature Partner Journal " Urban Sustainability ."

Follow the money: The research was funded by the National Science Foundation, the Cynthia and George Mitchell Foundation, the Jackson School of Geosciences and the UT Planet Texas 2050 initiative.

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