In a 3-1/2- or 4-quart slow cooker stir together chicken broth, turkey, mushrooms, the water, carrots, onion, soy sauce, ginger, and garlic.
Cover and cook on low-heat setting for 7 to 8 hours or on high-heat setting for 31/2 to 4 hours.
If using low-heat setting, turn to high-heat setting. Stir in bok choy and uncooked rice. Cover and cook for 10 to 15 minutes more or until rice is tender. Ladle into bowls. If desired, top with lo mein noodles.