Temporary artificial islands project underway near Grafton, Illinois

Potter US Army Corps of Engineers
Potter, a dredger operated by the US Army Corps of EngineersUS Army Corps of Engineers

The US Army Corps of Engineers (USACE), St. Louis District’s dredger Potter is currently working near Grafton, Illinois, between river miles 218 and 222, using a flexible floating pipeline to remove material from the navigation channel. The flexible pipeline allows for the creation of ephemeral islands that will be used for habitat restoration and mimics natural sand bar formation.

Due to rising water levels and since the dredge placement is unconfined using the energy of the river to distribute the sediment and shape the bar, these newly created ephemeral islands or sandbars may be underwater or unstable. It is therefore recommended that boaters avoid these temporary islands.

The USACE said a variety of fish and wildlife will benefit from these temporary, or ephemeral, islands and sandbars. Ephemeral islands, when exposed, provide safe feeding and resting habitat for a variety of shorebirds.

If exposed for long periods during the breeding season, these sand bars may also provide nesting habitat for species like the Interior Least Tern. When these temporary islands are underwater, they provide habitat for species of minnows and young fish.

Mariners should be on the lookout for tender boats, barges, small survey boats, and pipeline when transiting the dredge area. Recreational boaters should be vigilant of rising water levels, as increased flows can change the characteristics of how the river normally acts.

Increasing river currents meanwhile make it difficult for watercraft to manoeuvre safely and avoid debris. Boat operators are thus advised to exercise caution and wear lifejackets.

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