In the 1950s, the U.S. Army Corps of Engineers rose to the top of her list of enemies. In a major construction program, a complex system of canals, levees, dams, and pump stations was built to provide protection from seasonal flooding to former marsh land -- now being used for agriculture and real estate development. Long before scientists became alarmed about the effects on the natural ecosystems of south Florida, Mrs. Douglas was railing at officials for destroying wetlands, eliminating sheetflow of water, and upsetting the natural cycles upon which the entire system depends.