SRP201259 PRJNA548586 Calumet area hyperalkaline slag-fill metagenomes Environmental metagenomic reads were sequenced from several sites around the former Calumet Wetlands in south Chicago, IL, USA, to identify microbial taxa and functions related to the extreme alkalinity (pH 10-13+) in the slag-fill groundwater of the area. Weathering of steel slag deposits releases large amounts of Ca(OH)2, as well as heavy metals and potentially gaseous hydrogen. Interaction between the slag leachate and atmospheric CO2 at high pH produces abundant calcite precipitation. Together, these factors make this anthropogenic pollution site similar to natural serpentinizing springs. Metagenomic assemblies and 16S ribosomal RNA sequencing has found at Calumet a member of the bacterial genus Serpentinomonas, which is thus associated both with natural serpentinizating springs and similar, artificial environments. Future analyses of this bacterium will improve our understanding of bacterial hyperalkaline tolerance in freshwater systems, and may open new approaches to bioremediation of alkaline pollution.