Diatom community data from eight stream reaches at the Coweeta LTER/Coweeta Hydrologic Lab. Samples were collected in September 2005, January 2006, September 2018, and January 2019. For each stream, three replicate samples were collected over a 100 m stream reach from rock substrates. Diatoms were enumerated from permanent slides to the species level. For each sample, community data include relative cell densities and relative cell biovolumes. This data package is completed.