Spray Dutch oven with nonstick cooking spray. Add ground turkey, carrots, onion, celery, garlic and 1 tablespoon of the taco seasoning mix; cook over medium heat for 10 to 12 minutes or until turkey is no longer pink and vegetables are tender, stirring frequently.
Stir in water, tomatoes and remaining taco seasoning mix. Bring to a boil. Reduce heat; simmer 20 minutes, stirring occasionally.
Add barley; simmer an additional 15 minutes or until barley is tender, stirring occasionally. Stir in oregano.