Sprinkle the roast with 1 Tbsp. flour. In a Dutch oven, brown the roast on all sides in half of the butter. Add the water, bouillon, onion, celery, salt and pepper; bring to a boil. Reduce heat; cover and simmer for 1 hour. Add carrots; cover and simmer 45-60 minutes longer or until meat is tender. Remove meat and carrots to a serving platter and keep warm. Strain cooking juices; set aside. In the same Dutch oven, melt remaining butter. Stir in remaining flour; cook and stir until bubbly. Add 2 cups of the cooking juices and blend until smooth. Cook and stir until thickened; add additional cooking juices until gravy has desired consistency.