The Kootenai River is a large, oligotrophic river that relies on tributary resources to sustain the mainstem food web dynamics. Among these critical food resources are macroinvertebrates, particularly for higher-level consumers like fish. We examined the diel abundance of macroinvertebrate drift on three tributaries during three consecutive summers. Expected diel trends would follow cyclic patterns with peaks in drift abundance occurring at night. In this research, only a few samples conformed with what was expected. The remaining samples have peaks at different times of the day, either not following a clear cyclic pattern or having peak drift occur during the day. Site characteristics tend to influence the composition of macroinvertebrates present. The sites with lower water velocity have higher numbers of the mayfly Paraleptophlebia sp. and members of the family Corixidae, both macroinvertebrates that prefer slower-moving waters. Although there are differences in composition among site locations, some key taxa remain similar among all samples. The Baetis sp. mayfly is the most abundant macroinvertebrate for all but two samples, with an average abundance of 40.4% and a range of 1.7% - 71.2%. Macroinvertebrate drift is a critical component to understanding food resource availability in large oligotrophic rivers and promotes informed conservation strategies.