Lake Okeechobee and its watershed lakes and wetlands historically stored vast amounts of water from rainfall in the south-central Florida interior, south of Orlando. Most of this water was carried southward by the lake’s largest tributary, the Kissimmee River. The lake annually spilled into the Everglades, adding substantial water flow and hydroperiod to the already flooded ecosystem. With this function, Lake Okeechobee was the hydrologic hub of the South Florida ecosystem. Today, that function has been curtailed by flood control projects through the Kissimmee watershed and diversion of Okeechobee’s waters to the coasts, often in ecologically damaging heavy flows to the St. Lucie and Caloosahatchee, and altered flows to other coastal ecosystems. Containment of the lake by the Hoover Dike and water control has constrained the important littoral zone to the smaller lake, unable to move outward in response to changing water levels. Since about 1970, nutrient enrichment, mostly from agriculture, has changed the lake’s chemistry and threatened its biological functions. Nutrient enrichment was exacerbated by canalization of, and levees along, the Kissimmee River, and by the Hoover Dike. These modifications have served to retain entrained sediments in the river and lake rather than allowing them to exit and settle in the larger, natural wetlands and littoral zone, including the northern Everglades. The phosphorus load now embodied in lake sediments (greatly resuspended by the hurricanes of 2004 and 2005) may require centuries to assimilate, and unless loading of phosphorus from the watershed is substantially reduced, the internal recycling will never decline. Clearly, ongoing and planned phosphorus reductions and improved watershed storage are critical to improving the lake’s health. In the end, the ability to provide flood control and water supply without (1) impairing the ecology of Lake Okeechobee and (2) damaging the Caloosahatchee, St. Lucie, and other estuaries, is essentially hopeless without implementing expansions under Everglades restoration projects for moving much more treated water out of the lake and south to the Everglades.