A circular island in the middle of a Dutch lake might look like an unusual piece of land reclamation. But IJsseloog has a far more specific purpose: it was built to contain contaminated sediment removed from the lakebed. The project brings together water management, environmental engineering and an attempt to deal with pollution left behind by decades of industrial activity.
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| IJsseloog is an artificial island in the Ketelmeer, Netherlands, designed to contain contaminated dredged sediment. |
What is IJsseloog?
IJsseloog is an artificial island in Ketelmeer, in the Dutch province of Flevoland. Unlike an ordinary island, it was designed around an engineered depot for storing polluted dredged material. The name is often understood as “IJssel Eye", which aptly describes its distinctive circular appearance. Seen from above, the structure stands out against the surrounding water, making it one of the Netherlands’ more unusual examples of environmental infrastructure. According to the Dutch water authority Rijkswaterstaat, the depot covers approximately 235 hectares and has a capacity of about 23 million cubic metres. It entered service in 2000.
Why Was IJsseloog Built?
Ketelmeer receives water from the River IJssel, which carries sediment downstream from a much wider river system. Over decades, pollutants from industrial activity accumulated in the lake’s bottom sediments. Removing the contaminated material was important for the lake’s environmental recovery. However, dredging alone could not solve the problem: the sediment also needed a place where it could be contained rather than simply redistributed elsewhere.
The Dutch government therefore developed a dedicated storage depot in the lake. The Dutch National Archives documents the planning and construction of the Ketelmeer sediment depot, later named IJsseloog. Its records explain that the project aimed to collect contaminated sediment from Ketelmeer and other waterways.
First image credit: Hetblauwehart. Org
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| IJsseloog is an artificial island in Ketelmeer, the Netherlands, designed to contain contaminated sediment removed from the lake. |
How the Artificial Island Works
A large, enclosed underwater depot
IJsseloog is not simply a mound of dredged sludge piled above the water. The central storage area is a deep, circular basin enclosed by an embankment. Historical technical and archival sources describe a depot around one kilometre across, with a depth of roughly 45 metres below the water surface and a surrounding embankment rising above it.
The basin was engineered to isolate the contaminated material from the surrounding lake. Its design includes a sealing layer of clay, while monitoring and management measures help control the potential movement of pollutants. It’s important to keep it contained: It wouldn’t do much good to remove contaminated sediment from one place if it could get loose into adjacent waters.
What happens to the dredged material?
Dredging brings sediment up from the lakebed, after which it can be transported to the depot for storage. The material is not automatically suitable for reuse simply because it has been removed from the water.
Rijkswaterstaat explains that sediment is assessed before decisions are made about its destination. Clean material may sometimes be reused or returned to designated water areas, while contaminated dredged material must be handled appropriately and can be sent to a designated depot. Read its official explanation of Dutch dredging depots.
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| Seen from above, IJsseloog’s distinctive circular basin sits within an artificial island in Ketelmeer, the Netherlands, built to contain contaminated dredged sediment. |
Image credit: Hetblauwehart. Org
An Unusual Shape Visible From Space
These images offer more than an unusual view. They help explain why the depot is so distinctive: an environmental engineering project has become a clearly visible feature in the geography of the lake.
Does IJsseloog Help Nature Recover?
The depot was created as part of efforts to address contaminated sediment, not as a conventional nature reserve. Its contribution to environmental recovery depends on safe containment, responsible management and the wider restoration of the lake. The surrounding Ketelmeer landscape also has ecological value. The official Natura 2000 information for Ketelmeer and Vossemeer describes the area’s wetland and aquatic environment while also noting the legacy of polluted sediment.
IJsseloog illustrates an important point in environmental management: cleaning up pollution often requires more than removing it from sight. You have to handle the material and observe it over time. You also have to consider the ecosystem around it.
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| The unusual shape of IJsseloog is visible from above, revealing the engineered island built in Ketelmeer to contain contaminated dredged sediment. |
Frequently Asked Questions
Where is IJsseloog located?
IJsseloog is in Ketelmeer, near the mouth of the River IJssel, in the Dutch province of Flevoland.
Why was IJsseloog built?
It was constructed to hold contaminated sediment dredged from Ketelmeer and other waterways to address pollution that had built up in the lakebed.
How large is the IJsseloog depot?
Rijkswaterstaat lists an area of approximately 235 hectares and a capacity of about 23 million cubic metres.
Is IJsseloog a natural island?
No. It is an artificial island built around an engineered sediment-storage depot.
Can contaminated sediment be returned to the lake?
Not without assessment. The material’s quality determines whether it can be reused or returned to designated areas or must be safely contained in a depot.
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| The IJsseloog depot provides a contained storage site for contaminated sediment dredged from Ketelmeer, helping prevent the material from spreading into the surrounding environment. |
Conclusion
IJsseloog is an unusual landmark with a serious purpose. Its circular outline makes it look almost abstract from above, yet the structure was built to address a very real environmental problem beneath the waters of Ketelmeer. By providing a dedicated place for contaminated sediment, the project became part of the Netherlands’ wider approach to waterway management and pollution control. It is a reminder that some of the most curious human-made landscapes are not built to impress visitors but to solve problems that would otherwise remain hidden.
References & Sources
- Rijkswaterstaat — Official IJsseloog facts
- U.S. Geological Survey (USGS) — Satellite imagery and environmental background
- Natura 2000 Netherlands — Environmental and ecological context
- Rijkswaterstaat Publications — Original engineering project plan
- Rijkswaterstaat — Water-management and monitoring report
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