The National Park Service has been gathering water quality data in Biscayne National Park via continuous recording remote sensing systems since 1990. This data, collected at 6 locations with datasondes measured specific conductivity, dissolved oxygen, pH, temperature, turbidity, and tide height. In 1997, 12 additional datasonde locations were added to support a contract with the Corps of Engineers for data collection for development of a computerized circulation model for Biscayne Bay. The purpose of sampling water variables is to increase understanding of the Biscayne National Park/Biscayne Bay hydrological system. This information helps to provide reliable data for decision and policy making in water resource management. The annual plots for water quality monitoring give an overall trend for the year showing seasonal highs and lows based primarily on natural factors such as weather patterns, temperature fluctuations, and overland flow rates, mainly influenced by hurricane season and rainy season. The nearshore environment is most affected by surface runoff from nearby land and drainage canals.