Preheat oven to 350F. Lightly spray a 13 by 9 inch baking dish with nonstick cooking spray.
Combine browned beef, beans, oregano, cumin and garlic powder.
Place 4 lasagna noodles in bottom of baking dish. Spread half the beef mixture over noodles. Top with 4 more noodles and remaining beef mixture. Cover with remaining noodles.
Combine water and salsa. Pour over noodles. Cover with foil. Bake 1 1/2 hours or until noodles are tender.
Combine sour cream, onions and olives. Spoon over casserole and top with grated cheese. Bake, uncovered, until cheese melts. Remove and let stand for 10 minutes to set.