The 74-year-old structure near Augusta Regional Airport blocks upstream migration of the endangered shortnose sturgeon and other species -- and was earmarked for removal after a 1999 Army Corps of Engineers study found that it was no longer needed for commercial shipping, the purpose for which it was built.
Since then, efforts by local governments to save the dam -- and its 13-mile pool of water tapped by industries and cities -- yielded a congressional decree that it be repaired and turned over to local municipalities to maintain.
Congress never allocated the $22 million needed to renovate the dam.
Georgia's $600 million plan to deepen Savannah Harbor includes a series of mitigation measures to offset the inevitable damage to coastal habitats used by the shortnose sturgeon and its larger cousin, the Atlantic sturgeon.
One of those measures includes a $7 million fish passage structure that would allow fish to swim around New Savannah Bluff and access the miles of shoals and other habitat above Augusta.
The problem with that plan, however, is that it might provide no help for the sturgeon, which might not even use the device, according to Roy Crabtree, the regional administrator of the National Oceanic and Atmospheric Administration's National Marine Fisheries Service.
In a recent letter to Col. Jeffrey Hall, the corps' Savannah District commander, Crabtree said that adequate mitigation for the sturgeon will require re-establishing access above New Savannah Bluff and that the proposed fish passage device probably would not work.
At the very least, he wrote, extensive design changes will be needed, and even if an acceptable design could be agreed on, significant funding would be required to monitor and maintain the device forever.
"The removal of the New Savannah Bluff Lock and Dam is our preferred method to allow sturgeon access to upstream habitats," he wrote.
Although removing the dam would restore fish access to the river's upper reaches, it would also require -- literally -- an act of Congress, corps spokesman Billy Birdwell said.
"Our recommendation has always been that we should remove the thing," he said. "That has been the corps' standard position on this and on other facilities we no longer use, and that no longer serve their mission."
Currently, the dam remains in political limbo: Congress has ordered the corps to repair it and turn it over to the local governments, but never funded that mandate.
"The local governments won't take it until it is rehabbed, but Congress has not given us any appropriation to conduct the rehab," Birdwell said.
Crabtree's letter acknowledged that the corps would have to seek congressional authority to remove the dam, but said that the corps will already be approaching Congress to seek approval for the increased costs of the Savannah Harbor project.
"Combining these authorization requests presents an ideal opportunity to redress the environmental damage of the Corps of Engineers' legacy dam while advocating the modern economic benefits of the project," he wrote.
If the dam were removed, or if a fish passage structure were built, the completion of either project would trigger requirements for fish passage systems at two other dams above the city -- the Augusta Diversion Dam at the canal headgates, and the Stevens Creek hydroelectric dam owned by South Carolina Electric & Gas Co.
Both upstream dams are under pressure from the Federal Energy Regulatory Commission to provide fish passage, but both were allowed to place such projects on hold until such time as fish can move past New Savannah Bluff, which currently blocks most upstream migration.