This data package contains relative diatom taxon abundances collected annually during the wet season between 2005 and 2014 from sites distributed throughout the greater Everglades ecosystem. This project is part of the Comprehensive Everglades Restoration Program's Monitoring and Assessment Plan intended to document baseline variability in periphyton attributes for assessing the effectiveness of restoration projects. A total of 200 primary sampling units (PSU) of 800 m x 800 m are nested in 32 landscape units and each year, random coordinates are 'drawn' within each PSU and one sampleable draw is visited in each. Sampled periphyton is processed for diatoms, slides are prepared, and 500 frustules are enumerated and identified to the lowest possible taxonomic resolution per slide. Taxon abundances are then relativized to the total count. These data accompany environmental, periphyton biomass, and soft algal abundance datasets. Post-2014 data are available upon request to the project PI, Evelyn Gaiser.