Chemistry data (field and lab chemistry) is stored in the Chemistry_Samples and the Chemistry_Results table.  These tables are linked by a foreign key based on the Site_ID and Field_ID fields.  Each Sample has one entry in the Chemistry_Samples table, and numerous results in the Chemistry_Results table.

The Chemistry Samples table references the Locations table for information about the sampling location (ie co-ordinates etc..), the Wells table for information about the groundwater wells or screened intervals.

A number of reference tables are referred to, in particular the Matrix Types table, and the Chemistry Lookup table.

The key tables and relationships are shown below.