SAVANNAH — A federal agency said Tuesday that machines designed to inject extra oxygen for fish to breathe in the Savannah harbor passed a second round of tests that were required as part of the $973 million deepening of the shipping channel to the Port of Savannah.
The Army Corps of Engineers released a 172-page report that concluded testing last summer found the injection machines successfully offset a small loss of dissolved oxygen in the water as the river gets deepened to make room for larger cargo ships.
The Army Corps spent $100 million to build a pair of stations on the Savannah River equipped with large machines that suck in water, swirl it with oxygen pulled from the air and inject the mixture back into the river that's home to blue crabs, striped bass and endangered shortnose sturgeon.
A 2013 legal settlement with environmental groups who sued over the harbor deepening required the Army Corps to prove that the machines worked.
Southern Environmental Law Center attorney Chris DeScherer, who represented the groups in the federal lawsuit, said he had not yet reviewed the Army Corps' entire report. He said he has concerns about the government's commitment to operate the machines long-term at an estimated cost of $3 million per year.
"We remain skeptical about a plan to use these mechanical devices in perpetuity without a guaranteed source of funding to effectively solve this problem over such a large segment of the river," DeScherer said in an emailed statement.
When the Army Corps previously reported a successful first round of testing in 2019, DeScherer expressed similar doubts. Still, environmental groups chose not to resume a court fight over the project.
The South Carolina Department of Health and Environmental Control, which as also a party to the 2013 legal settlement, did not immediately return an email seeking comment.
The Army Corps said its second round of tests found two oxygen-injection stations on the river pumped an average of 40,000 pounds (roughly 18,000 kilograms) of oxygen into the river daily from late July through late September. It concluded the oxygen mixed well throughout the water column.
The injectors will run each year during the hottest months of the year from June through September, when oxygen levels in the river tend to be lowest.
The agency says next year it should finish deepening the 27-mile (43-kilometer) shipping channel that links the Savannah port to the Atlantic Ocean.