As part of a biodiversity conservation effort in Izmit Bay on the western coast of Türkiye, a total of 1.4 million cubic meters (49.4 million cubic feet) of seabed sludge has so far been removed, and visible improvements have been recorded in the water and sediment quality of the region.
Launched jointly by the Ministry of Environment, Urbanization and Climate Change and Kocaeli Metropolitan Municipality, the “Eastern Basin Seabed Sludge Removal, Dewatering and Disposal Project” has been ongoing since May 2, 2023, on the eastern side of Izmit Bay.
At a 70-decare site (17.3 acres) established at the former Izmit fairgrounds, sludge suctioned from the sea via ship-connected pipelines is processed through dredging and dewatering stages before being transported to a storage area.
In the project, which aims to remove 3.8 million cubic meters of seabed sludge from a total area of 468 hectares, 1.4 million cubic meters have already been extracted from 170 hectares. Aerial images show clear improvements in the cleaned sections, where the water and seabed have returned to normal. In contrast, the untreated sections still appear brownish in color.
Mesut Önem, head of the Environmental Protection and Control Department at Kocaeli Metropolitan Municipality, explained that this is one of the largest environmental projects in Europe, carried out in partnership with the ministry. He stated that the project began with the goal of cleaning the seabed sludge in Izmit Bay.
Önem said the project aims to protect the ecosystem and leave a cleaner environment for future generations, adding, “Izmit Bay is the pride of our region, and we conduct a wide range of operations here from inspections to marine litter collection.”
He emphasized the need to clean this section of the Marmara Sea and explained that, based on research by Scientific and Technological Research Council of Türkiye's (TÜBİTAK) Marmara Research Center and Istanbul University, they aim to remove 3.8 million cubic meters of sludge from 468 hectares in the eastern basin.
The project, structured in three phases, has so far cleared 1.4 million cubic meters from 170 hectares. “To put it in perspective, we’ve cleaned an area the size of 250 football fields,” said Önem.
“That’s about 100,000 truckloads of sludge removed from the marine ecosystem. With this seabed cleaning, we’re restoring water circulation and biodiversity. We’re working with universities and scientific institutions to ensure the success of this initiative,” he said.
Biodiversity monitoring is being conducted in the cleaned areas by Istanbul University’s Faculty of Aquatic Sciences, and Türkiye’s longest-running water quality monitoring project has been ongoing since 2007 in partnership with the TÜBİTAK Marmara Research Center. A “digital twin” model of the project has also been developed with the Middle East Technical University’s Institute of Marine Sciences and Gebze Technical University to monitor the 12 streams flowing into Izmit Bay.
Önem added that Kocaeli University has helped create artificial reef zones, and that 54,000 fish, including turbot, sea bass and gilthead seabream, have been tagged and released into the bay under the “Izmit Bay Fish Restocking Project” from 2017 to 2025.
He also reported a rise in both the number and diversity of fish as a result of the ongoing restoration efforts.
Following the 2021 mucilage crisis, Önem stressed that the municipality strictly adheres to the Marmara Sea Action Plan issued by the Ministry of Environment. “We don’t discharge even a single drop of untreated wastewater into Izmit Bay,” he said.
Noting the importance of staying vigilant, he continued: “At the end of last year and into this year, mucilage was observed in various parts of the Marmara Sea, both on the surface and underwater. So far, Izmit Bay has not experienced mucilage. But that doesn’t mean we’re immune. We’re doing everything we can to prevent it. We’re committed to fully implementing all 22 measures outlined in the Marmara Sea Action Plan to ensure mucilage doesn’t return to Izmit Bay.”
