Table schema:
CREATE TABLE table_name_21 (rank INTEGER, county_and_state VARCHAR, capacity__thousands_of_metric_tons_ VARCHAR)

Question: In Silver Bow County, Montana, when the capicity is more than 45 tons, what's the highest rank found?
SQL: SELECT MAX(rank) FROM table_name_21 WHERE county_and_state = "silver bow county, montana" AND capacity__thousands_of_metric_tons_ > 45