A pilot project using dredged sediment from Mobile Bay to create 3D-printed artificial reefs has shown promising results, leading to plans for a larger deployment.

The Mobile Bay National Estuary Program is working with the U.S. Army Corps of Engineers, Mobile District, to expand the project after an initial test showed the structures could withstand conditions in the bay and provide habitat for marine life.

Henry Perkins, private sector program lead for the Mobile Bay National Estuary Program, said the idea originated with the Corps of Engineers, which has been looking for new ways to put dredged material to use.

"This is a U.S. Army Corps of Engineers project that we are kind of implementing through them and doing all the monitoring," Perkins said.

The project started with researchers in the U.S. Army Engineer Research and Development Center in Vicksburg, Mississippi. Corps employee Alan Kennedy secured funding to develop the printer and used sediment dredged from Blakely Island to create the first reef structures.

The effort is aimed at solving a problem that comes with maintaining the Mobile Ship Channel. Every year, millions of cubic yards of sediment are removed to keep the channel open for shipping. Coarser materials can often be reused, but the fine silty sediment has few practical uses.

Earlier this year, lawmakers approved the Save Our Bay Act, legislation aimed at ending the practice commonly known as mud dumping in Mobile Bay. The law prohibits placing dredged sediment from shipping channels into the open waters of the bay, where environmental advocates say it can cloud the water and smother sensitive habitats such as oyster reefs, seagrasses and other aquatic life.

Mud dumping, which the U.S. Army Corps of Engineers refers to as thin-layer placement, involves dispersing sediment across the bay's surface. The Corps has said the practice mimics the natural movement of sediment, but environmental groups have argued that the sheer volume of material being released can negatively affect water quality and benthic habitats.

"This process takes that stuff, cooks it into a reef, and then we're testing whether or not that's suitable for habitat and things like shoreline protection," Perkins said.

Field work on the pilot began in October 2025 when the Mobile Bay National Estuary Program placed a reef and several test pieces near a dock on Mon Louis Island. The goal was to find out whether the material could survive wave action, changing tides and winter weather.

"Our main question was, will this hold up?" said Blair Morrison, science and monitoring program lead for MBNEP. "Overall, all of our pieces have stayed; our reef has stayed intact."

The results were encouraging. Not only did the structures remain in place, but marine life quickly began using them. Organisms attached themselves to the surface, and small fish and other animals gathered around the reefs.

"We've seen some really encouraging biofouling," Morrison said. "We're getting things like barnacles, different kinds of algae, bryozoans."

Researchers have also observed grass shrimp, juvenile crabs and several species of small fish around the structures.

The reefs themselves are made from clay-rich sediment collected from the bay. After being dewatered, the material is shaped with a 3D printer and fired at low temperatures. Morrison described the finished product as "high-tech terracotta."

One design resembles a dome with openings around the sides and a hollow center, creating places where marine life can attach and shelter.

"I call it the beehive because it's kind of like a dome structure that has some holes in it," Morrison said. "There's also a cavity in the middle of that structure so things can actually live inside it as well."

Adding hard surfaces back into the bay gives oysters, algae and other organisms places to grow while creating habitat for fish and crabs.

"Hard structure in the bay has been depleted," Morrison said. "Adding hard structure back to the bay can help jumpstart some of these benthic habitats."

The next phase of the project will move beyond a single reef. Researchers plan to deploy nine structures in different environments around the bay. Some will include ground oyster shells mixed into the material, while others will have whole shells attached to the outside to encourage oyster growth.

"Oysters are kind of a keystone species here that we're trying to see if we can attract," Perkins said.

The new reefs are expected to be placed this summer, allowing researchers to monitor whether oyster larvae settle on the structures during spawning season.

"We're hoping to try and catch some of the oyster spawning season to see if we start getting oyster spat settling on those surfaces," Morrison said.

Researchers say the larger goal is to determine whether the process could be expanded for future restoration projects. Producing reef material locally could reduce the need to transport rock and other materials from elsewhere in the state.

Supporters say finding productive uses for dredged sediment could provide an alternative to disposal methods that have long been debated in Mobile Bay. If the material proves effective for reef building and shoreline restoration, it could transform what has often been viewed as a waste product into a resource for habitat creation.

"If this material works, if this is a tool we can add to our beneficial use toolbox, then we have to figure out how we can scale this," Perkins said.

Morrison said the project could help change the way people think about dredged sediment.

"Turning the narrative from this kind of fine-grain sediment as being a waste product or some burden in terms of disposal, making this a resource that can be used for habitat creation, for shoreline restoration, really providing more tools and technologies where we can flip that script is one of the things that I think us and all of our partners are really invested in," she said.

Both Perkins and Morrison credited the U.S. Army Corps of Engineers for developing the project and thanked Dauphin Island property owner Andy De Paola for allowing the first reef to be placed near his dock.

"We just really want to highlight them and kind of credit their forward thinking on this," Morrison said. "We're excited to continue our collaboration in the future." 

Gabriella Chavez is a Report for America corps member who writes about growth and development in Baldwin County and our natural spaces for Gulf Coast Media. Your donation to match our RFA grant helps keep her writing stories like this one; please consider making a tax-deductible gift of any amount today by visiting https://tinyurl.com/yaf8yf5n.