This dataset contains particle starting location files for particle tracking simulations of the Upper Missouri River near Wolf Point, MT using the “Fluvial Particle” particle tracking model (https://doi.org/10.5066/P9K1U4O0). The file “DriftExperiment_StartLocations_n30000.csv” corresponds to particle simulations of a July 1, 2019, larval drift experiment. This file is configured to simulate 30,000 particles run in serial (i.e., 30,000 particles run on a single CPU). The files “ReachComparison_StartLocations_Lower_n250.csv” and “ReachComparison_StartLocations_Upper_n250.csv” correspond to particle simulations comparing the upper and lower sub-reaches of the larger model reach. Each of these simulations also used 30,000 particles but were configured to be run in parallel with 250 particles run per CPU. It should be noted that while the column headers are not included in the file due to it being formatted to be read by "Fluvial Particle". This dataset contains five different columns. The first represents time, the second is the x-coordinate, the third is the y-coordinate, the fourth is elevation, and the final is the number of particles released at that location.