Chow Mein Casserole

1 can mushroom soup
1 small green pepper, chopped
1 cup celery, chopped
1 can tuna fish in spring water, drained
1/4 cup milk
1/4 cup onion, chopped
1 cup chow mein noodles

Mix all ingredients except chow mein noodles in your slow cooker. Cover and cook on low for 7 - 8 hours. Add chow mein noodles during the last hour of cooking.