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Rising Waters Q&A: Readers ask about big ships in the harbor and plastic bans

The container ship Cezanne makes its way through Charleston Harbor past fishermen as it heads to the South Carolina Ports terminal in August 2021.

Posted on December 20, 2023

Every month, we receive questions and concerns from people in and around Charleston related to flooding, government regulations and sea-level rise. We read every single one. Now we are answering some of them in the pages of The Post and Courier. Our Rising Waters Q&A appears every other Monday. Email your questions to and

This month, you asked us about the large ships in the harbor and how the city of Charleston enforces its plastic bans.

Here’s what we found out.

What are the environmental impacts of those big ships coming in and out of the harbor?

Larger container ships can enter Charleston Harbor as a result of the Post-45 Charleston Harbor Deepening Project, which was completed in December 2022 and made the harbor’s shipping channel the deepest in the U.S. at 52 feet.

Army Corps Chief of Programs and Civil Works Jeff Livasy said the Corps considered the environmental impacts of the deepening effort and of larger ships traversing the harbor before the project began.

“What the team came back with is that by deepening the harbor, there would be larger vessels, but they would come with less frequency,” Livasy said. “So, larger ships and fewer ships overall.”

The Army Corps considered how the wave energy from the ships would impact shorelines. They found that the energy created by wind and tidal events was much greater and more frequent than the wave energy created by large ships passing through.

“The ships are such a small, small fraction, like less than 1 percent of the overall energy in the harbor,” Livasy said.

Larger ships can deliver more goods than smaller ships, theoretically decreasing the total number of ships that would have to enter the harbor to deliver the same amount of goods prior to the deepening.

Most of these container ships burn a residual fuel oil, also called bunker fuel, which is among the least refined and highest-polluting. Burning this type of fuel not only produces carbon emissions, but also particulate matter, which can affect air quality.

“Our deepened harbor enables us to handle bigger ships, which are often newer and more energy efficient,” South Carolina Ports Authority spokesperson Liz Crumley said. “We can now handle more cargo on fewer vessels, producing fewer emissions overall.”

The container ships entering the harbor since the deepening project have gotten larger and are carrying more cargo. Now, vessels carrying 15,000 containers at a time are common.

The Post and Courier reported in 2022 that the number of containers processed through Charleston Harbor has more than doubled since the early 2010s. In 2022, the Ports Authority handled nearly 2.8 million shipping containers.

Crumley says the number of container ships traversing the harbor before and after the deepening project are “roughly the same.”

The containers these ships carry measure 20 feet long and carry tires, vehicles, raw materials and parts needed by manufacturers, lumber, clothing, furniture, electronics, home goods, appliances, toys, agricultural goods, refrigerated and frozen food and medicine.

“Every time you order something online, buy something in a store or drive your car, you are likely doing so because of a connection to shipping,” Crumley said, adding that ship sizes will continue to grow as market demands grow.

The Army Corps doesn’t monitor air quality or water quality impacts of larger ships. It does monitor the potential impacts the harbor deepening project may have on water quality, including changes to salinity and dissolved oxygen levels. A report on these findings is expected to be released in 2028.


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