Melt butter in a large stock pot over low heat; add flour, stirring until smooth. Cook over medium heat, stirring constantly, until roux is the color of a copper penny. Add water, okra, tomatoes, onion, salt, pepper, garlic powder, thyme, and Creole seasoning; bring mixture to a boil. Reduce heat, and simmer 1 hour.
Add remaining ingredients, except rice, and simmer, uncovered, an additional 15 minutes, stirring frequently.
Serve gumbo over hot cooked rice in individual bowls.