Lemony Chicken and Orzo Soup

Place the chicken, carrots, onion, and lemon in a 5- to 6-quart slow cooker. Using kitchen twine, tie the dill and parsley together and nestle it among the chicken and vegetables. Add the broth and 2 cups water, cover, and cook until the chicken is cooked through and easily shreds, 7 to 8 hours on low or 4 to 5 hours on high. Thirty minutes before serving, transfer the chicken to a bowl and the carrots and onion to a cutting board. Discard the lemon and herbs. Strain the liquid (if desired) and return to the slow cooker. Cut the celery into 1/4-inch pieces and add it to the slow cooker along with the orzo. Cover and cook on high until the orzo is tender, 20 to 25 minutes. Meanwhile, cut the carrots into rounds and cut the onion into 1/4-inch pieces. Shred the chicken into large pieces, discarding the bones. Just before serving, return the chicken, carrots, and onion to the slow cooker along with the snap peas and cook for 3 minutes. Serve with extra dill, if desired.