Place carrots and mushrooms in a 4- or 5-qt. slow cooker. Sprinkle roast with garlic powder and pepper. In a large skillet, brown roast in oil on all sides. Transfer to slow cooker., Combine the gravy, mushroom soup, water and onion soup mix; pour over roast. Cover and cook on low for 6-8 hours or until meat is tender. Skim fat from gravy if necessary; serve gravy with beef.