Application of GIS-PLAT in Analyzing Phosphorus Loads in the Lake Okeechobee Basin

Lake Okeechobee is the second largest freshwater lake in the United States. It covers 1732 km² and is an important water source for the Everglades ecosystem and for meeting the diverse water needs of South Florida. However, during the last 25 years eutrophication processes in the lake have accelerated due in part to large quantities of non-point source nutrient inputs from predominantly agricultural land uses. The major nutrient of concern is phosphorus, primarily generated from intensive beef cattle and dairy farming activities located in tributary basins north of the lake. In 1989, a regulatory permitting program was implemented by the South Florida Water Management District to monitor total phosphorus concentrations in runoff from land use activities surrounding the lake. As a result of this regulatory program off-site discharge total phosphorus concentration limitations of 0.18 mg/L to 1.20 mg/L were developed for application on all non dairy land uses in the lake's northern tributary basins. More than 700 permits have been issued since the inception of this regulatory program. Water quality monitoring is conducted on each permitted parcel for a minimum of one year after issuance of the permit to determine compliance with the established total phosphorus concentration limitations.