Thompson Engineering – Stabilization and Restoration of Fish River Tributary

Thompson Engineering is a proven leader in the planning, designing, and construction of major transportation, economic development, and waterfront projects across the Southeast.

In 1987, Congress established the National Estuary Program (NEP) under a provision of the Clean Water Act. Across the country, individual NEPs are place-based, which means they focus only on restoring and protecting their own estuaries and watersheds. 

Through a combination of residential/commercial development and apparent previous channel realignments, Marlow (Spring Creek) was undergoing a physical transformation, resulting in excessive erosion and sedimentation into Fish River. The erosion and head cutting also jeopardized the upstream roadway structure at County Road 9. Hurricane Sally had exacerbated the erosion, and a solution needed to be in place before another storm event. Baldwin County leaders sought solutions and needed one quickly.

Through funding from the National Fish and Wildlife Foundation, Thompson Engineering was contracted by the Mobile Bay National Estuary Program to perform restoration services in this area. The restoration satisfied several goals by improving ecosystem function, reduction of streambank and floodplain erosion, infrastructure risk reduction, and deposition of sediment into Fish River.

The stream restoration provided the following benefits:

• Improved the floodplain habitat
  Improved aquatic and channel habitat of the stream
• Improved fish habitat for native species including fish passage
• Improved riparian buffer width, species diversity and functions of stability, habitat, and aesthetics
• Improved the floodplain ecological functions of water storage
• Improved the aesthetic potential of Spring Creek to be enjoyed by the community.
• Increased opportunities for public education about the Spring Creek watershed and ecological restoration
• Reduced potential for upstream flooding
• Reduced sediment erosion rate and sediment transport rates to the Fish River

The stabilization and restoration of the tributary created a healthier watershed by improving ecosystem function, shrinking streambank and floodplain erosion, and reducing pollutants running into Fish River, including an estimated 548,000 lbs. of sediment, 822 lbs. of phosphorus and 6,128 lbs. of nitrogen.

Project partners included:

• Thompson Engineering, Inc. – Design and engineering services
• 5 Smooth Stones Restoration, PLLC – Design services
• Hydro Engineering Solution, LLC – Stream modeling
• Streamline Environmental, LLC – Construction services

Besides the benefits of restoration from an environmental standpoint at this site, the results obtained during the 5-year long-term monitoring program will provide information for future engineers and scientists to use on other sites to enhance their knowledge on site selection, design, and construction, all helping to improve water quality and habitats.