Table 2. Column name and description for lake chloride data file.

Column Name	Description
SALT_ID	Internal lake ID number
FileName	File name
Common.Name	Name of lake or reservoir that is commonly used
Station	Sampling station ID. The ID is program specific and is included to cross-reference sites with original sources. For some lakes, data are present from multiple stations.
Sample.Date	Date of sample collection. All data were collected on discrete days, with the exception of early data from Lake Mendota and Monona (see Methods).
Sample.Depth	Depth of sample collection
Chloride	Chloride concentration in mg l−1
Decimal.Date	Sample date provided as decimal value
Std.Chloride	Chloride concentration provided as a standardized z-score value, which was calculated for each lake
Integrated.Depth	Is TRUE if sample was integrated over a portion of the water column. Is FALSE otherwise. If a sample depth is given, this was the starting depth of sampling.