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Watershed Management Lab

Apalachicola Slough Restoration

Sloughs and other low-velocity areas of river systems such as the Apalachicola River, provide an important refuge habitat for several organisms, yet mismanagement of the river system has caused many of these sloughs to fill with sand. The Slough Restoration Project, funded in 2020 by the National Fish and Wildlife Foundation’s Gulf Environmental Benefit Fund, will restore the connection of three slough systems in the Apalachicola River watershed during times of low flow by removing sediment plugs and reestablishing hydrologic connectivity. Our research focuses on the evolution of the regions water quality as the project progresses. 

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Project Summary 

Led by Ph.D. student Love Kumar, we’re examining how restoration of sloughs will benefit water quality in these important ecosystems. The Apalachicola River and Estuary system is of exceptional ecological importance, and constitutes one of the least polluted, most undeveloped, resource-rich systems left in the United States. Apalachicola Bay depends on the Apalachicola River, its seasonally flooded floodplain, and its floodplain sloughs, which support the Bay ecosystem with fresh water, nutrients, detritus, and connected habitats (Chanton and Lewis 2002, Elder et al, 1988). The Apalachicola River sloughs are extensive, extending nearly 300 mi, almost four times the length of the river, and provide important habitats for fish, mussels, and other organisms. The roughly 400 sloughs naturally connect with the river at different flows, in direct correlation to of the elevation of their inlet (Light et al 1998). The impacts to these floodplain sections from the disconnection of the mainstem are well documented and restoration in the major loop stream systems is important to the overall health of this ecosystem.

Sand deposits in a slough raise the required river level needed to connect the slough and floodplain to the mainstem. As sloughs are bypassed, water remains in the mainstem and is transported directly to the lower bay. The system loses the ability to store river water benefiting the floodplain and extending the hydroperiod of freshwater to the bay during low-water conditions. The constraint is exacerbated by the continued increases of withdrawals upstream to support stakeholder uses. The impacts of the last few decades have manifested in the significant loss of bottomland forested floodplain. These sand “plugs” were especially devastating during the last decade of extended droughts. Where once, floodplain was fed by these connecting sloughs the blockages now significantly restricted flows which would have been the only source of freshwater in these low-flow periods.

This project is a partnership among UF researchers, National Fish and Wildlife Foundation, and Apalachicola Riverkeeper. Our project has three main objectives:

  1. Measurement of streamflow in Spider, Douglas and East River slough. This measurement will help us assessing the flow of water to floodplains during low period and its effect on natural ecology.
  2. Real time water quality assessment from all three-slough site. Water quality results will provide the connection of water quality with flow between low flow and high flow time.
  3. How does water level in the slough correlate with water level in the floodplain and the river?
  4. We are curious to see the restoration in East River slough will be enough to affect the water chemistry of Bay.
  5. Understanding the scale at which these types of restoration project influence the estuarine system this study will provides information to prioritize restoration activities in future slough systems.