We recently asked readers what topics they would like to read about on Balancing the Basin, and someone asked us for an update on the New Savannah Bluff Lock and Dam. Here’s the comment we received:
“I would like to know the Corps’ views on the future of the New Savannah Bluff Lock and Dam. Now that the lock has been declared unsafe, will the dam be the next to go? Also, I am curious about the fish passage planned to bypass the lock and dam. It seems to me that the fish passage idea is based on sketchy science. Am I wrong? Thanks. I appreciate your excellent communications work.”
First, to address the lock and dam closure: We closed the lock on May 15 due to public safety concerns from deterioration under the riverside lock wall. The dam portion and associated gates remain operable. While we do not expect a collapse of the lock wall, there are concerns with the lock wall foundation that exceed prudent safety levels. Visitors can still access the landside of the lock for fishing. You can read more about the lock and dam closure in our May 8 blog post here: http://1.usa.gov/1yLkgG8
While operation of the lock has been suspended indefinitely, there are no plans to tear down either the lock or the dam. In the Water Resources Development Act of 2000, Congress authorized the Corps to rehabilitate the lock and dam and transfer ownership and operation of the structure to the City of North Augusta and Aiken County, South Carolina. However, Congress has not appropriated federal funds for that rehabilitation.
As for the fish bypass, the design is based on the best science available. An interagency team identified the design parameters that the bypass would need to include. We have worked very closely with Blair Remy Architects, the lead design firm, to design the bypass so that it performs as intended.
The fish bypass is one of several environmental mitigation features under the Savannah Harbor Expansion Project (SHEP). Deepening the harbor would allow saltwater to travel further upstream into areas currently used by endangered shortnose and Atlantic sturgeon. The increased salinity would reduce the suitability of some of these areas. The natural resource agencies could not identify anything the SHEP could do in the estuary to reliably mitigate those adverse impacts. They agreed that the fish bypass would adequately compensate for those impacts, allowing fish to access historical spawning grounds at the Augusta Shoals.
The fish bypass was designed using the current water control manual; therefore it will not cause or influence any changes in operations at the Thurmond Dam—a concern cited by several stakeholders in the area.
The fish bypass will divert the river around the South Carolina side of the lock and dam. The design is considered an off-channel rock ramp and would look like a collection of boulders in the river making river rapids. Water will flow constantly down the rock ramp.
Here’s the basic operational concept: The five gates at the dam will remain closed when inflows are less than 8,000 cfs. This would cause 100 percent of the river flow to pass down the off-channel rock ramp. When the river flows above 8,000 cfs, the gates can be opened to pass the higher flows through the dam as needed. Read more about the fish bypass in our May 15, 2013 blog post here: http://1.usa.gov/1rtXi5y
The design is 100 percent complete and has been peer-reviewed by NOAA Fisheries and the Georgia Department of Natural Resources. Once construction for the SHEP begins, the fish bypass will be one of the earlier contracts awarded. The fish bypass includes a five-year environmental monitoring period
Thanks for your feedback and for reading Balancing the Basin. We welcome your questions and comments in the comments section below.
~Tracy Robillard, public affairs specialist