user: Question: What is the date construction is completed in Jo Daviess county?
Columns: ['CERCLIS ID', 'County', 'Listed', 'Construction completed', 'Partially deleted', 'Deleted']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['ILD980607055', 'Adams', '08/30/1990', '03/31/1999', 'N/A', 'N/A']
SQL:

assistant: SELECT "Construction completed" FROM "Table" WHERE "County" = 'Jo Daviess';