Water Supply and Wastewater Infrastructure System Challenges Under Climate Uncertainty

Water supply and wastewater treatment infrastructure systems in Texas face rising challenges under the combined pressures of climate change and rapid population growth. By examining historical records and future projections, this chapter presents a comprehensive assessment of reservoir supply resilience and wastewater hazard risk across Texas. A comparative study evaluates the relationships between reservoir storage and both historical and projected drought trends, as well as population trends. Additionally, municipal water use stress is examined under current and future streamflow scenarios, as well as the intersection of streamflow changes with wastewater system performance. Long-term changes in reservoir storage and interannual change detection from 2008 to 2024 reveal consistent declines in storage levels, well below conservation storage capacity. A comparison of monthly historical streamflow and seasonal storage trends reveals pronounced regional differences in seasonal storage strategies under flow surplus and deficits – this pattern is likely to be exaggerated under future streamflow projections through the mid- and late centuries under varying climate scenarios. Multi-model projections indicate a long-term trajectory toward increased drought severity, particularly in West Texas. Simulated reservoir responses to drought by previous studies, including the benchmark 1950s drought, underscore the diminishing reliability of water supplies under various future demand levels for selected reservoirs serving the Dallas–Fort Worth region. In parallel, the spatiotemporal assessments of municipal water use stress indicate a shift toward extreme stress conditions across much of Texas. Wastewater systems also face localized risks from declining streamflow-driven dilution capacity, leading to potential environmental health hazards. Statewide non-attainment potential (based on dilution capacity) is already high but remains relatively stable under future scenarios, even with increased effluent discharge conditions. The chapter concludes by emphasizing the need for integrated water resource strategies and resilient wastewater infrastructure planning that can dynamically respond to both climatic change and socioeconomic shifts.