Skip to main content

TMDL Development for the Savannah Harbor Estuary: Problem, Approach, and Tools

Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

The Savannah Harbor Dissolved Oxygen TMDL is the most controversial TMDL performed by EPA Region 4 and has had an extensive track record of public involvement along with Federal and State agencies in a technical review role. The Savannah Harbor Estuary has numerous anthropogenic, hydrological, and meteorological factors that influence the dissolved oxygen concentrations. The dominating anthropogenic factors are the discharge of wastewaters from large industrial and wastewater facilities; withdrawals of freshwater by power plants for urban supplies; and pollution by nonpoint source runoff. In addition to anthropogenic sources, there is an extensive marsh system that exports natural sources of BOD from vegetation decay along with a large BOD source in the Atlantic Ocean. The hydrological regime of the estuary is complicated by spring tides on the order of 10–12 feet in range and freshwater flow distribution between interconnected parts of the estuary: the Savannah River, the Front River, the Middle River, the Little Back River, the Back River, the South Channel, and the offshore portions in the Atlantic Ocean, as well as numerous meandering channels and marshes.

The Savannah Harbor Estuary is bathymetrically complex, with shallow 3–6 meter parts of the harbor, cut by a 14-meter ship channel that follows through the Front River up to Port Wentworth. Water, salinity, and temperature balance are forming under the influence of tidal intrusions of the ocean waters and freshwater flow from upstream parts of Savannah River.

The hydrodynamic and water quality models were put under extensive scrutiny by the Federal and State agencies that would be using the model for NPDES permits, a dissolved oxygen TMDL, harbor deepening impacts, and a dissolved oxygen ecosystem restoration study. Previous modeling efforts of the Savannah Harbor were determined to be lacking defensibility on the handling of the vertical mixing numerical scheme, boundary conditions, and resolving the upstream portions of the river. The Federal and State agencies wanted one management tool for the harbor that could be used on the various studies. Therefore, the grid resolution, the boundaries, inputs, and outputs had to be approved by a working technical group through the process.

The Environmental Fluid Dynamics Code (EFDC) and the US EPA Water Quality Analysis Simulation Program (the latest version-WASP 7.0) was applied to the harbor and calibrated to a 1999 dataset and validated to a 1997 dataset. The WASP model was used for the nutrient enrichment, eutrophication, and dissolved oxygen depletion dynamics. The water quality model allows for simulating a response in dissolved oxygen, nutrients, and chlorophyll-a concentrations as a function of various loading and transport scenarios. The model has a user-friendly interface that eases the problem of input files creation and model output analyzing. The hydrodynamics are critically important for simulation of transport of water quality constituents. The WASP 7.0 has the option of adopting the information from the output of the EFDC model. The EFDC modeling package has been well tested for simulating three-dimensional flow and transport in complex environments including rivers, estuaries, and in the offshore shelf. The EFDC model has a highly accurate transport scheme that provides a capability to resolve sharp gradient problems that are typical for salinity regimes in shallow estuaries.

The model domain is located near Savannah, Georgia and is on the border between Georgia and South Carolina. The domain extends upstream on the Savannah River to river mile 61.0 near Clyo, Georgia. The downstream end of the model extends approximately 17 miles offshore from Oysterbed Island to cover the navigational channel of Savannah Harbor.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Data/Media
No Metrics

Document Type: Research Article

Publication date: 2005-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more