Bring water to a boil in a small saucepan; stir in barley. Cover, reduce heat, and simmer 12 minutes or until tender. Remove from heat and let stand, covered, 5 minutes. Place barley in a colander and run under cold water until completely cooled. Drain well.
Combine mushrooms and next 10 ingredients in a large bowl.
Add barley and blue cheese to mushroom mixture; toss gently. Let stand 5 minutes before serving.