Coal ash disposal poses persistent environmental risks due to the potential release of toxic trace metals into adjacent aquatic systems. This study evaluated coal ash–related contamination in the White River near Noblesville, Indiana, where legacy, unregulated coal ash landfills remain in close proximity to the river despite the 2015 Coal Combustion Residuals (CCR) Rule. The objective was to assess spatial patterns of trace metal contamination in surface water and sediments and evaluate implications for water quality. Water and sediment samples were collected from five locations, including two upstream and three downstream of the landfills. Water samples were acid-preserved (HNO₃, pH <2) and analyzed via ICP-MS (EPA Method 6020B; Hg via 7470A). Sediments were oven-dried (40 °C), homogenized, sieved (<60 µm), digested (EPA 3051A), and analyzed using ICP-MS.Dissolved arsenic ranged from 1.95–3.75 µg/L, with slightly higher concentrations observed downstream. Boron was consistently detected and showed clear downstream enrichment, increasing from 71.1 µg/L upstream to a maximum of 104 µg/L downstream bottom waters. Cadmium was generally below detection (<0.077 µg/L) but was detected at one downstream site (0.331 µg/L). Lead was mostly below detection (<0.45 µg/L) except for localized downstream detections (up to 7.69 µg/L). Selenium remained below detection (<0.89 µg/L) across sites, and mercury was not detected (<0.13 µg/L). Mean downstream sediment concentrations of As (≈2.21 mg/kg), Pb (≈11.0 mg/kg), B (≈5.30 mg/kg), Cd (≈0.29 mg/kg), and Se (≈0.24 mg/kg) exceeded upstream values, indicating metal accumulation in reaches adjacent to the landfills.Overall, sediments in the White River act as a long-term reservoir for coal ash–associated trace metals, with clear downstream enrichment indicating continued influence from adjacent legacy disposal sites. Dissolved-phase detections of boron, arsenic, and localized lead further support evidence of metal transport within the system. Although metal mobility appears constrained under the hydrologic conditions sampled, shifts in hydrology or sediment disturbance could enhance remobilization from stored sediment pools.This study establishes a critical geochemical baseline for the White River near Noblesville and provides essential data to support the Indiana Department of Environmental Management (IDEM) and local policymakers in strengthening coal ash landfill oversight, enhancing long-term surface water monitoring, and protecting the ecological integrity of the White River system.