Calcium and pH data collected at lake, reservoir, impoundment and stream site types in the Columbia River Basin. These data were downloaded from the National Water Quality Portal on 03/31/2022 and cleaned and filtered. We limited calcium data to just those values that described dissolved calcium and total calcium concentrations. We included total calcium to maximize the amount of data available for this risk assessment; dissolved and total calcium are strongly correlated since dissolved calcium is a constituent part of total calcium. We then cleaned these data by filtering to just those entries associated with water (‘ActivityMediaName’ = Water); dropping rows with ‘NA’ values; removing white spaces; removing duplicated entries; removing negative controls (e.g., field and lab blanks); removing sites associating with mining activity or mining reclamation; standardizing units (mg/L for calcium), and; removing values outside of a sensical range (e.g., 0-14 for pH). These filtering and cleaning steps reduced the number of observations from 932,239 to 567,581.