CREATE TABLE table_name_71 (river_mile NUMBER, pool_length__miles_ VARCHAR2, lock_lift_drop__in_feet_ VARCHAR2)

What is the highest River Mile that has a pool length of 42.2 miles or a lock/lift drop of 21 feet?
SELECT MAX(river_mile) FROM table_name_71 WHERE pool_length__miles_ = "42.2" AND lock_lift_drop__in_feet_ = "21"
SELECT MAX("river_mile") FROM "table_name_71" WHERE "21" = "lock_lift_drop__in_feet_" AND "42.2" = "pool_length__miles_"