Preheat the oven to 350 degrees. Grease a 9×13 inch baking dish. In a large skillet over medium heat brown the ground beef, breaking it apart into crumbles as it cooked (about 8 minutes). Drain excess fat. Stir in taco seasoning, water, chili powder, cooked rice, salt, garlic salt, black pepper, and 1 can of tomato sauce. Mix until thoroughly combined. Bring to a boil, reduce heat to low and simmer for 20 minutes.
While the ground beef is simmering, cut bell peppers in half lengthwise, and remove the stems, membranes, cores, and seeds. Place a steamer insert into a large saucepan, and fill with water to just below the bottom of the steamer. Cover and bring the water to a boil over high heat. Place the peppers into the steamer insert, cover the pan, and steam until just tender (about 3-5 minutes).
Place steamy peppers into the prepared baking dish and fill each pepper lightly with the meat filling. Spoon the remaining can of tomato sauce over each pepper. Cover the baking dish with aluminum foil.
Place into the oven and bake at 350 degrees until the peppers are tender and the filling is hot (about 25 to 30 minutes). During the last few minutes of cooking, remove the foil and top each pepper with Colby-jack cheese. Bake until the cheese has melted.