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Fat threeridge mussel   Biologists weigh Gulf sturgeon
  Photos: FWS


Apalachicola-Chattahoochee-Flint River Basin

Biological Opinion Available

As part of the Endangered Species Act consultation process (§7), the U.S. Fish & Wildlife Service has evaluated the U.S. Army Corps of Engineers’ (USACE) Update of the Water Control Manual (WCM) for the Apalachicola-Chattahoochee-Flint River Basin (ACF) in Alabama, Florida, and Georgia.  The action proposed by the USACE is primarily the operation of its 5 federal facilities (dams), individually and in concert, under the WCM.

ACF River Basin Map
Click Map for PDF

The Water Control Manual.  In the WCM, the USACE adopts a modified version of its preferred alternative action (PAA) from the Draft Environmental Impact Statement (DEIS).  The WCM incorporates actions for fish and wildlife conservation, including actions for federally-listed species (e.g., water releases below Woodruff Dam on the basis of spawning, non-spawning, and winter requirements), tailrace dissolved oxygen levels, fish passage, reservoir fish spawning, and management of Eufaula National Wildlife Refuge.  The WCM also includes actions for drought operations, flood risk management, hydroelectric power generation, navigation, recreation, water quality, and water supply.  Compared to existing management, the USACE proposes to modify 1) the action zones, 2) drought operations, 3) storage relocation at Lake Lanier, 4) ramping during prolonged flow, and 5) navigation.

Steps used to develop the Biological Opinion

1. USACE Assessment.  The USACE prepared a Biological Assessment (BA) to review whether its proposed WCM would affect endangered species or their habitats.  In the BA, the USACE concluded that the proposed action may adversely affect the fat threeridge, purple bankclimber, and Chipola slabshell, but would not likely adversely affect (NLAA) their designated critical habitat.  Additionally, USACE determined that the proposed action may affect, but is NLAA, the Gulf sturgeon and its designated critical habitat. 

  • 2. USFWS Review.  In its independent review of the proposed USACE action and the BA, the USFWS included new information and analyses for Gulf sturgeon and did not concur with the USACE's determination of NLAA for the Gulf sturgeon and its designated critical habitat.  The USFWS concluded that the proposed changes in operation would affect the Gulf sturgeon.  Therefore, effects on mussel species and sturgeon and their critical habitats are addressed in this biological opinion (BO). 


  • 3. Status of the Species and Effects Analysis.  The current status of Gulf sturgeon and the three mussel species and the critical habitat for all four species is discussed in detail in this BO.  The principal factor we examine is the flow regime of the Apalachicola River and how the flow regime affects habitat conditions for the listed species.  The proposed update to the WCM provides both beneficial and adverse effects to the species and designated critical habitats we have assessed. 


  • 4. USFWS Biological Opinion.  Using the best available science, the USFWS developed its biological opinion based on an analysis of the potential effects of the WCM on the endangered and threatened species and their habitats.  The document includes a description of the proposed action and species affected, an analysis of effects, and conclusions.


Conclusion.  The USFWS recognizes that the ACF River basin is a working river that provides water, transportation and livelihood for residents of three states.  The USACE will use its WCM as a guide to balance the uses for recreation, water supply, navigation, hydroelectric generation, flood control, drought reduction, fish and wildlife habitat, and endangered species. 

  • • The Service is committed to ensuring that the development of water resources is compatible with the conservation of America’s fish and wildlife resources.
  • • The BO requires the Corps to incorporate adaptive management approaches that will allow the Corps to improve how it implements the Water Control Manual to protect endangered species and their habitats in response to changing flows, droughts, and changing climate.  This is an opportunity for the Corps to better understand the impacts of its operations, and to contribute to the recovery of these species and conservation of their habitats in the Apalachicola River.              
  • • The Service expects to continue to work with the Corps and state agencies to monitor the response of sensitive mussels and fish to flow conditions resulting from the operation under the Water Control Manual.  
  • • Actions required in this version of the Water Control Manual are only slightly different from prior operations, but provide better balance for droughts and changing circumstances.

Next Steps.

  • • The Corps has not officially adopted the proposed WCM yet.  The Assistant Secretary of the Army will use the BO and information from their draft EIS to make a final decision later this year.
  • • By law, the BO only considers endangered and threatened species.  Impacts of the Corps’ operations on other important resources, such as the Apalachicola Bay oyster industry, were considered in the Corps’ EIS.
  • If you have specific questions, please send those via email to:

Additional ACF Information



Last updated: April 17, 2018