Major influences and findings for water quality and biology in southern Florida, including the Everglades, are described and illustrated. Samples were collected to determine total phosphorus, dissolved organic carbon, pesticides, mercury, nitrate, volatile organic carbon compounds, and radon-222. Water-management, agricultural, and land-use practices are discussed. Sixty-three species of fish in 26 families were collected; 43 native species, 10 exotic or nonnative species, and 10 species of marine fish that periodically inhabit canals and rivers were identified.