M.S. Applied Data Science - Capstone Chronicles 2025

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Figure 11 Arsenic Forecast in the next 10 years

The Arsenic forecast is characterized by a relatively flat baseline of approximately 5–8 µg/L, very near the U.S. EPA MCL of 10 µg/L, with mild seasonal increases in late summer. Historical outliers (up to 2,500 µg/L) contributed to modestly wider confidence bands early in the forecast but have little influence on the long ‐ term median trend. By 2035, median arsenic is expected to hover just below the MCL with 95 % upper bounds occasionally brushing 12 µg/L implying that several water systems may periodically exceed regulatory limits. Given arsenic’s severe chronic health impacts, these findings highlight the urgency for both sustained treatment (e.g., adsorption media or reverse osmosis) and community outreach in the handful of counties where projected exceedance probability remains non ‐ negligible.

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