Marine sediments harbor a vast amount of Earth’s microbial biomass, yet little is understood regarding how cells subsist in these low-energy environments without forming endospores. DNA methylation, a reversible process that involves the addition of a methyl group to a nucleotide base via a methyltransferase, exists as a possible epigenetic mechanism for non-sporulated cells in low-energy sediment environments to regulate gene expression and potentially lower cellular activity. To investigate the presence and scope of this phenomenon in estuarine sediment microbial communities, we sequenced three metagenomic and 16S rRNA gene amplicon libraries extracted from a sediment core collected from the banks of the Oyster Rocks site of the Broadkill River, Milton, Delaware, USA. We targeted 5-methylcytosine at CpG sites by digesting metagenomic libraries with the methylation-sensitive restriction endonuclease HpaII. By quantitatively distinguishing “mixed” methylation states for populations of CpG site copies, we identified dynamic, non-binary shifts in CpG methylation for community taxa and function.