Broccoli Rice Casserole

Cook broccoli and rice according to package directions. Preheat oven to 350 degrees F (175 degrees C).
In a medium saucepan over low heat, mix cream of mushroom soup, cream of chicken soup, and 1 1/4 cups water. Gradually stir in cheese until melted. Be careful that the cheese doesn't burn.
Melt butter in a large skillet over medium-high heat, and cook and stir celery and onion until soft.
In a large mixing bowl, combine broccoli, rice, soup and cheese mixture, celery and onion. Season with salt and pepper. Pour mixture into a 9x13 inch baking dish.
Bake in the preheated oven for 45 minutes, until bubbly and lightly brown.