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Abstract: An estimated 229 000 m3 of coal fly ash remains in the river system after dredging to clean-up the 2008 Tennessee Valley Authority (TVA) spill in Kingston, Tennessee. The ash is heterogeneous with clear, orange and black spheres and non-spherical amorphous particles. Combustion produces iron oxides that allow low field magnetic susceptibility (χ LF) and percent frequency dependent susceptibility (χ FD%) to be used to discriminate between coal fly ash and sediments native to the watershed. Riverbed samples with χ LF greater than 3.0 × 10−6 m3/kg, have greater than 15% ash measured by optical point counting. χ LF is positively correlated with total ash, allowing ash detection in riverbed sediments and at depth in cores. The ratio of ash sphere composition is altered by river transport introducing variability in χ LF. Measurement of χ LF is inexpensive, non-destructive, and a reliable analytical tool for monitoring the fate of coal ash in this fluvial environment. [Copyright &y& Elsevier]