94-3 A Century of Urban Infrastructure Degradation and its Impact on Water Resources

Session: Geoscience and Water: How Geoscience Affects Water-Related Public Policy–Past, Present, and Future

Presenting Author:

Josiah Sananda

Authors:

Sananda, Josiah M.¹, Banner, Jay L.², Nachimuthu, Sneha³, Black, Bryan A.⁴, Abella-Gutierrez, Jose⁵, Faust, Kasey M.⁶, Loewy, Staci L.⁷

(1) Department of Earth and Planetary Sciences, The University of Texas at Austin, Austin, Texas, USA, (2) Department of Earth and Planetary Sciences, The University of Texas at Austin, Austin, TX, USA, (3) Department of Earth and Planetary Sciences, The University of Texas at Austin, Austin, Texas, USA, (4) Laboratory of Tree Ring Research, The University of Arizona, Tucson, Arizona, USA, (5) Department of Earth and Planetary Sciences, The University of Texas at Austin, Austin, Texas, USA, (6) Fariborz Maseeh Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas, USA, (7) Department of Earth and Planetary Sciences, The University of Texas at Austin, Austin, TX, USA,

Abstract:

The unintentional input of municipal water into natural streams contributes to water quality degradation as part of “Urban Stream Syndrome”, a growing challenge amid rapid 21^st-century urban expansion and mounting water stress. Understanding how this input impacts natural hydrologic systems requires water quality records over timescales of city growth, yet such data are rare on these decadal to century timescales. We develop a tree-ring proxy using Sr isotopes (⁸⁷Sr/⁸⁶Sr) in bald cypress to reconstruct temporal changes in the proportions of municipal versus natural water in three streams in Austin, Texas. In an urban watershed, persistently elevated tree-ring ⁸⁷Sr/⁸⁶Sr values from 1940-2021 reflect municipal water contributions of 87 - 97%. A rural watershed has maintained low ⁸⁷Sr/⁸⁶Sr values since the 1840s, indicating minimal municipal influence. In a rapidly urbanizing watershed, a resolvable 20% increase in municipal water contribution to streamwater is observed starting in the 1990s, coinciding with the onset of recent development. These findings indicate that infrastructure may begin to fail within 2-3 decades of installation, underscoring the need for planning infrastructure resilience into cities as part of their expansion. This resilience will conserve water, minimize Urban Stream Syndrome, and reduce the costs and carbon footprint of urban water systems.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10387

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