Services Rendered:

EFDC 3D Thermal Model

Groundwater Pumping Impacts on Estuary Salinity

Manatee Thermal Habitat Analysis

Data Regression

Joint Probability Analysis

Climate Change


Southwest Florida Water Management District Tampa,



Michael G. Heyl

Chief Environmental Scientist

(813) 985-7481

Dates of Performance:

Nov 2007 to Mar 2009

Status of Project:


The Southwest Florida Water management District (SWFWMD) was in the process of developing methods and rules for the establishment and implementation of Minimum Flows and Levels (MFL) for priority water bodies within its jurisdiction. As part of their methods development process and to address a specific priority site they contracted DSI to provide the following for the Chassahowitzka River/Estuary System:

  • Development of a three dimensional hydrodynamic model with salinity and temperature state variables.
  • Determination of the areas in the Chassahowitzka system that meet manatee habitat criteria during critical conditions.
  • Determination of salinity changes and the resulting changes in the volume, area and shoreline lengths of salinity regimes due to reductions in spring flows due to groundwater extractions and climate change.

DSI under the direction of SWFWMD, conducted a data assessment and statistic regression for missing data periods, calculated the joint probability analysis to establish the baseline critical condition of MFL for providing adequate protection to the manatee refuge. The 3D hydrodynamic (salinity and temperature) model was calibrated using USGS stations along the river’s centerline. This model was then used to develop the minimum baseline refuge areas/volumes and determine the changes in salinity regimes due to reductions in spring discharges.