Difficulty in morphological species identification, evolving and varying taxon concepts, morphological references based on non-regional specimens, and nomenclatural changes can lead to significant inconsistencies in taxonomic datasets across analysts and through time. This is particularly true for diatom taxonomy and even highly trained taxonomists can contribute to analyst bias that may overwhelm environmental signals. Facilitating taxonomic consistency among taxonomists is imperative to ameliorating this persistent problem, particularly for large, long-term datasets. For the 2018/2019 U.S. Environmental Protection Agency National Rivers and Streams Assessment (NRSA) diatom analysis, involving over 1,900 samples from across the contiguous U.S., we used an image voucher approach. Pre-analysis, images were taken of specimens from 80% of the diatom samples. Images were sorted into likely morphological species, assigned operational taxonomic units (OTUs), and organized into genus groups to create searchable taxonomic vouchers. Six analysts from different organizations used these vouchers as the sole taxonomic reference for NRSA data collection, ensuring consistent taxonomic concepts. This large-scale effort produced nine diatom reference vouchers based on the nine aggregate NRSA ecoregions as well as a “living” taxon table that tracks all taxonomic changes through time and is traceable back to the original OTU image sets. In addition to ameliorating inconsistencies among taxonomists, this approach is meant to move North American taxonomy away from European-based nomenclature by using the Diatoms of North America (DONA) website (diatoms.org) when adding species epithets to OTUs. It is our intent that these vouchers and the taxon table be used as a reference for other North American-based projects and that the taxonomy be informed by other experts in the field.