Using 26 'Urban Areas' with populations ranging between 50-thousand and 7-million persons as a national sample, close to one-sixth of urban lands in the U.S. lie within natural 100-year flood plains, and slightly over one-half of such flood plains already have been developed. Average annual flood damages for urban areas may be about three-fifths of the national total. Slightly over half of the national investment in flood control works have been for the protection of urban areas. Information available does not permit estimation of implied benefits. In comparison, well over one-half of urban lands are served by systems of underground drainage that represent over four times the capital investment in flood plain protection and are associated with approximately the same level of average annual flood damages. Much of the flood-plain flooding problem as well as the land-runoff water quality problem could possibly be myre effectively countered on the land feeding urban watercourses, provided planning and development of drainage systems and flood plain management programs can be coordinated and integrated. Specific recommendations are made on acquisition of needed information. There are implications for emerging national water policies.