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?
CREATE TABLE "largest_generating_stations" (
  "rank" real,
  "name" text,
  "capacity_mw" real,
  "province" text,
  "type" text
);
SELECT MIN("rank") FROM "largest_generating_stations" WHERE "type"='hydro' AND "name"='grand rapids generating station' AND "capacity_mw">479;