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The St. Marks River and Apalachee Bay watershed covers about 1,168 square miles of north Florida and south Georgia. The surface watershed interacts as a dynamic system with the underlying aquifers that are the source of the springs that contribute much to the baseflow of the watershed’s rivers and to the character of the region. The watershed includes Florida’s capital city and smaller coastal communities, as well as large undeveloped regions including forestland, extensive coastal marshes buffering the Gulf of Mexico, and state parks and public and private conservation lands that protect and sustain natural resources. Physiographically diverse, this watershed includes the red hills region of north Florida and south Georgia, sand hill remnants of historic shorelines, and large portions of the Woodville Karst Plain.

The watershed is known for its unique geological features and distinctive landforms that make up the Woodville Karst Plain. Due to the presence of limestone at or near the land surface, rainfall readily moves into and recharges the Floridan Aquifer, the region’s underground drinking water supply. Over time, this water has dissolved the carbonates of the aquifer and has resulted in many karst landforms. The karst plain is characterized by an abundance of springs, sinks, sinking streams and swallets.

St. Marks River and Apalachee Bay SWIM Plan

The purpose of the St. Marks River and Apalachee Bay SWIM plan is to provide a framework for resource management, protection, and restoration using a watershed approach. Protecting and restoring watershed resources is a shared responsibility on the part of numerous watershed stakeholders, including local governments, state and federal agencies, private businesses, and the public. It requires building upon past accomplishments to encompass a wide range of management approaches. Addressing continuing challenges affecting water quality and natural systems requires a range of strategies. Among these are additional improvements in the treatment and management of stormwater runoff; continued implementation of best management practices for agriculture, silviculture, and construction; and additional efforts to improve wastewater treatment and management. To complement these, long-term protection of critical habitats and associated buffer areas will further help protect water resources. Projects identified in the plan include the following:

  • Stormwater Planning and Retrofit
  • Septic Tank Abatement
  • Advanced Onsite Treatment Systems
  • Woodville Karst Springs Water Quality Protection and Enhancement
  • Agriculture and Silviculture BMPs
  • Riparian Buffer Zones
  • Aquatic, Hydrologic, and Wetland Restoration
  • Estuarine Habitat Restoration
  • Strategic Land Conservation
  • Watershed Stewardship Initiative
  • Sub-basin Restoration Plans
  • Wastewater Treatment and Management Improvements
  • Interstate Coordination
  • Analytical Program Support
  • Comprehensive Monitoring Program

For more information, please contact Paul Thorpe at or (850) 539-5999.

Supporting Documents

Water Supply Assessments

Hydrogeology of the Northwest Florida Water Management District

Lower St. Marks River/Wakulla River/Apalachee Bay Resource Characterization

Ground Water Chemical Characterization of the St. Marks River Rise (2006)

Nitrate Loading as an Indicator of Nonpoint Source Pollution in the Lower St. Marks-Wakulla Rivers Watershed