user: Question: what is the lowest rank when the type is hydro, the name is grand rapids generating station and the capacity (mw) is more than 479?
Columns: ['Rank', 'Name', 'Capacity ( MW )', 'Province', 'Type']
Types: ['real', 'text', 'real', 'text', 'text']
Sample row: [1.0, 'Bruce Nuclear Generating Station', 7276.0, 'Ontario', 'Nuclear']
SQL:

assistant: SELECT MIN("Rank") FROM "Table" WHERE "Type" = 'hydro' AND "Name" = 'grand rapids generating station' AND "Capacity ( MW )" > 479.0;