Deep-well injection of liquid waste is being evaluated in Florida as a management option to help alleviate environmental deterioration of fresh and estuarine waters and increasing problems of waste disposal. Extensive areas of Florida are underlain by permeable saline-aquifer systems that are separated from overlying freshwater aquifers by low-permeability confining materials consisting of clay, evaporites, or dense carbonate rocks. These deep saline zones are the subject of current research designed to assess the environmental impact of subsurface waste storage. Three active deep-well disposal systems currently exist, and two additional systems are under construction. Industrial and municipal wastes are injected into subsurface environments of different hydrogeologic characteristics at depths ranging from 1,400–3,000 ft. Transmissivities of the receiving carbonate aquifers range from 6,500 gpd per ft in northwest Florida to more than 17,000,000 gpd per ft for the cavernous Boulder Zone in southern peninsular Florida