SELECT MIN(rank) FROM table_name_67 WHERE type = "hydro" AND name = "grand rapids generating station" AND capacity___mw__ > 479
Berapa peringkat terendah saat jenisnya adalah Hydro, namanya Grand Rapids Generating Station dan kapasitas (MW) lebih dari 479?
CREATE TABLE table_name_67 (rank INTEGER, capacity___mw__ VARCHAR, type VARCHAR, name VARCHAR)