Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

The Bureau of Watershed Management, Florida Department of Environmental Protection (FDEP) has organized a number of Sections to coordinate and implement the total maximum daily load (TMDL) program. In particular, the Watershed Assessment Section (WAS) is responsible for data analysis and modeling applications to quantify TMDLs. The Section also develops and reviews recommendations for point and non-point source reductions needed to meet the TMDLs.

The State of Floridas Impaired Water Rule (IWR) has specified procedures for the listing or delisting of waters using all available ambient surfacewater data from previous surveys. During past surveys, WAS environmental professionals collected a wide range of biological, physical, and chemical data necessary for TMDL assessment. These FDEP data have been organized into the FDEPs Impaired Water Rule (IWR) database.

The majority of the IWR data were collected as part of ambient monitoring programs or in support of point source discharge permits. However, they are increasingly being reviewed for use in calibrating and verifying state-of-the-art computer models that have been developed for TMDL studies.

At this moment, the most challenging modeling effort is to establish TMDLs for dissolved oxygen (DO) and nutrients. The processes controlling DO are difficult to quantify since they are time varying on many scales and involve interactions between nutrients, the sediments, atmosphere, and other constituents. Typically, the data in the IWR database were collected monthly or quarterly in the daytime, and those data will not be sufficient to describe a dynamic system such as a tidal area or dissolved oxygen diel phenomena.

In response to the data needs to support computer modeling, the FDEP has developed an intensive data survey for supplementing the IWR database with the necessary data for DO and nutrient TMDL based modeling in the Saint Lucie Watershed and Estuary. To fulfill this purpose, the WAS staff has designed intensive surveys which include hourly meteorological data, flow data, continuous hourly data collected by probe, bi-weekly or quarterly grab samples for water quality, sediment oxygen demand, and water quality data collected by ISCO samplers during and after storm events.

The paper: