The 225 square-mile Upper Myakka River watershed is a hydrologically altered system in Southwest Florida. Taylor Engineering (as Interflow Engineering) prepared an integrated hydrologic model of the upper watershed using the MIKE SHE and MIKE-11 integrated surface and groundwater model. In 2017, Taylor Engineering updated the model to extend model datasets and simulations through year 2014, re-evaluate excess flows to Flatford Swamp, and to simulate new scenarios involving injection of excess water into the Upper Floridan Aquifer. The model consisted of a multi-layer groundwater model coupled with rainfall, irrigation, evapotranspiration, overland flow, streamflow, and vadose zone processes. Taylor successfully calibrated the model to nine USGS streamflow gage locations, fifteen surface water level measurement locations, and eight groundwater level measurement sites for a seven-year calibration period. The calibrated model served to evaluate past anthropogenic impacts, investigate the linkage between land use and hydrologic changes, and predict future long-term water budgets and water supply potential. Taylor Engineering evaluated several extraction, storage, and delivery alternatives for an alternative water supply, including a reliability assessment for a 1-billion gallon above-ground reservoir. Taylor also worked with SWFWMD staff to develop a set of minimum flows to maintain seasonal salinity levels within the Charlotte Harbor Estuary for maintenance of acceptable spatial extents of critical estuarine habitats. We used our MIKE SHE/MIKE 11 model of the upstream watershed to predict daily inflows to the estuary for several scenarios. These flows served as the freshwater boundary inflows to the Charlotte Harbor estuary.