Multiple linear regression models were developed to calculate lake fluctuation that occurs between 10 percent, 50 percent, and 90 percent of the time lake surface elevation is exceeded. A total of 48 lakes were selected from Hillsborough, Pasco, Highlands and Polk counties, which were identified as natural lakes through the study the Southwest Florida Water Management District (SWFWMD) conducted in 1999 and 2002 to develop the models. "Natural lake" refers to lakes that were not impacted by ground water pumping. Among these 48 lakes, 22 lakes from Hillsborough and Pasco counties sit in the coastal lowlands area. 26 lakes from Highlands and Polk counties are located in the Upland and Highlands Ridge area. In developing multiple regression models, the 48 lakes were divided into two groups, the same group of lakes that SWFWMD used to develop the Reference Lake Water Regime, the method that is used to set the minimum lake levels in the region. Further, these two groups of data were subdivided into four categories based on their physical characteristics. 22 lakes were divided into surface water flow through lakes (SWF) and surface water drainage lakes (SWD). 26 lakes used their county line as the divider to separate them into Highlands County lakes and Polk County lakes. A total of six sets of multiple regression models were developed to predict the lake stage fluctuation for lakes that have no or limited lake stage data. The Polk County date set provides the best model with R2 at 0.9. However, due to the lack of available information on lake basin characteristics, the models that were developed for Hillsborough and Pasco counties do not provide a good prediction.