The study of lakes, ponds, rivers, streams, swamps, and reservoirs that make up inland water systems. Each of these inland aquatic environments is physically and chemically connected with its surroundings by meteorologic and hydrogeologic processes .

Aquatic systems with excellent physical conditions for production of organisms and high nutrient levels may show signs of eutrophication. Eutrophic lakes are generally identified by large numbers of phytoplankton and aquatic macrophytes and by low oxygen concentrations in the profundal zone. Ecology Eutrophication Fresh-water ecosystem Hydrology Lake River