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Fish and Wildlife Service Completes Biological Opinion on Corps’ Revised Interim Operations Plan at Woodruff Dam


June 2, 2008


Tom MacKenzie, (404) 679-7291,
Gail Carmody, (850) 769-0552

The U.S. Fish and Wildlife Service today released a biological opinion on the U.S. Army Corps of Engineers’ Revised Interim Operations Plan (RIOP) for water releases at Jim Woodruff Dam into the Apalachicola River, saying it would not appreciably reduce the likelihood that the four listed species can survive nor would it preclude their future recovery.

The opinion will be in effect for five years (June 1, 2013), unless significant new information on predicted hydrology or the listed species prompts a reinitiation of consultation, or the Corps completes their Water Control Plan revision.

“This opinion relies once again on the best available science and data for its conclusions,” said Sam D. Hamilton, Southeast Regional Director, U.S. Fish and Wildlife Service. “We will continue to work with the Corps to use adaptive management, so when new data becomes available and as conditions change, we will collaborate to assess the situation and adapt to best meet the needs of the many users of the system.”

The Corps’ revised plan provides increased storage throughout the system – water stored at Lanier, West Point, and Walter F. George. Increased storage facilitates lake level recovery and maintenance and, if extreme drought conditions continue, provides water to augment Apalachicola flows in the summer and fall, when basin inflow falls below 5,000 cfs.

“Water use planning needs to be a higher priority for the states and agencies,” Hamilton said. “This proposal is but another step in a long series of challenges dealing with a limited resource. The time is now for the three states to develop a more sustainable plan.”

The species that is likely to be affected the most is the fat threeridge mussel, which could lose up to nine percent of its population. The fat threeridge population in the Apalachicola River appears to be declining largely because of drought conditions. Analysis has found that the additional effects of reducing minimum flows one time would be minor. Repeated instances of mortality caused by low flows could represent a serious problem for the species in the future. The Corps’ drought zone concept will serve to avoid and minimize reductions in minimum flows.

On April 15, 2008, the Corps requested that the Service consult on the impact to listed species of the revised interim operating plan. The four species that the Service reviewed in the Biological Opinion are the Gulf sturgeon, fat threeridge mussel, purple bankclimber mussel and Chipola slabshell mussel.

The Gulf sturgeon, a large, long-lived fish is a threatened species due to historic overfishing and construction of dams, impeding its ability to reproduce. The Gulf sturgeon is found in the large river basins from Louisiana to Florida. The freshwater mussels are also long-lived and are no longer found in much of their historic range due to construction of dams, channel changes, and water quality degradation. The fat threeridge is an endangered species, and was formerly found at a number of locations in the Flint River in Georgia and the Apalachicola and Chipola rivers in Florida. While the species is now found at many locations on the Apalachicola, only a few individuals have been found on the Flint or Chipola rivers. The purple bankclimber, a threatened species, is still found in much of its former range including the Ochlockonee River in Florida and Georgia, the Flint River in Georgia, and the Apalachicola River. The Chipola slabshell is found on the Chipola River in Alabama and Florida. It is a threatened species and included in the analysis because the Revised Interim Operating Plan affects the lower Chipola below the Chipola Cutoff.

The analysis of effects to river hydrology and potential effects to the listed species is complex. The Service’s analysis shows the Corps’ operational plan has beneficial and negative effects on the species. The beneficial effects include low flow augmentation to maintain 5,000 cubic feet per second (cfs) when water use in the basin and drought conditions might result in flows less than 5,000 cfs. Another beneficial effect is a decrease in the maximum number of days per year less than 16,000 cfs that shortens some periods of high salinity in the bay. However, there is an overall decrease in acres of floodplain inundated. Other adverse effects occur when the flows of the river abruptly change (also known as fall rates).

The Incidental Take Statement (ITS) that accompanies the opinion addresses the loss of individual fat threeridge (21,000), purple bankclimber (200) mussels, and Chipola slabshell (100) should there be a need to reduce the minimum flow of the Apalachicola River to 4,500 cfs in an extreme drought. In addition, loss of Gulf sturgeon eggs and larvae will occur when rapidly declining flows expose spawning sites.

In recorded history, there have only been a handful of days where flows of the Apalachicola River have been less than 5,000 cfs. There were no days below 5,000 cfs in the time before the reservoirs were built. Under the Revised Interim Operations Plan, the Corps will consistently ensure a minimum flow below the dam of 5,000 cfs, except in extreme drought when the minimum flows will be reduced to 4,500 cfs. While there is a possibility that a reduced minimum flow might be implemented this summer (2008), current conditions do not indicate that this will be needed. Once the reservoirs, particularly Lake Lanier refill, the Corps’ models indicate that the 4,500 cfs will not be triggered in the future because of the increased opportunities for storage identified in the RIOP. However if municipal and industrial consumption have a significant increasing trend, consumptive water use could cause the drought zone minimum flow to be triggered in droughts similar to those experienced in 2000 and 2007.

The Service’s biological opinion makes a number of recommendations for discretionary actions that would enhance conservation of mussels and Gulf sturgeon, and improve our understanding of the effects to fish and wildlife and to the ecosystem of the river and bay. The entire biological opinion, species fact sheets, and questions and answers about it are available at

“We will continue to work closely with the Corps on their efforts to manage if exceptional drought conditions continue and will provide technical assistance in the Water Control Planning process,” said Hamilton.

It is important to note that a biological opinion is a comparison of a federal proposed action with the baseline that includes conditions that the listed species are living in today. A biological opinion is not a retrospective look at all of the federal actions before the consultation. Therefore, the opinion on the RIOP does not address the construction of the reservoirs and their operation.

Hamilton went on to say that the river system is used for many purposes, including power generation, flood control, navigation, drinking water, pollution dilution, agriculture, and recreation.

“It will take everyone working together to be a part of protecting and restoring this national treasure so that the bountiful resources, including the seafood and recreational fishing of the world-renowned Apalachicola Bay are here for generations to come,” said Hamilton.

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