FDEP Klosterman Bayou, Model Development, Watershed and WQ Modeling (FL, USA)

Introduction

The Klosterman Bayou Watershed is a 3.22-square mile (2,072 acres) watershed located on the central-west coast of Florida. The entire watershed lies within Pinellas County, under the jurisdiction of the Florida Department of Environmental Protection (FDEP), in its southwest regulatory district (Southwest Florida Water Management District or SWFWMD). The tidal segment of Klosterman Bayou (Waterbody Identification unit or WBID 1508) is impaired for dissolved oxygen due to nutrients and biologic oxygen demand (BOD), based on assessments of the surface water quality data collected between 1999 and 2006.

Project Goal

To develop Total Maximum Daily Loads (TMDLs) for the tidally influenced and impaired segment of Klosterman Bayou (WBID 1508), set up, calibration, and validation of a watershed pollutant loading model and a receiving water quality/hydrodynamic model for dissolved oxygen and nutrients were required.

Stevenson Creek, Florida

Application

DSI conducted the receiving water quality modeling component of the project. A three-dimensional (3D) water quality model of the tidally influenced reach of Klosterman Bayou was developed using the Environmental Fluid Dynamics Code (EFDC) model. The water quality model simulated the full nitrogen and phosphorus components, as well as the carbon/BOD loadings to the Bayou and the impact due to actual discharges from the watershed.

The EFDC model flow boundary conditions were linked to the flow and nutrient loadings from the HSPF provided results provided by CDM, who conducted the HSPF calibration/validation work. The HSPF/EFDC linkage was streamlined using the latest updates to EFDC+ Explorer.

Once calibrated (2002) and validated (1999), the model was completed and the TMDL base for the period 1999 to 2006 was set up. This model was then used by FDEP to develop the recommended dissolved oxygen and nutrient TMDLs for Klosterman Bayou.