View north from the highway ridge at Cape Girardeau, Mo. showing a complete section of the flood wall. The floodwall will save the city from its almost annual flood battering. The city on the average will have a flood in the future only every 100 years. a $131,000,000 floodwall protection project is in the works for St. Louis and will start this year. St. Louis is the last major river city without any protection from floods on the Mississippi. Estimated cost of the Cape Girardeau project is $5,985,000. Photos from Army Corps of Engineers.