Jan 25, 2019

USACE Plans to Build Islands Using Dredged Mississippi River Sediment

The islands, built using dredged river sediment, would restore wildlife habitat and act as a barrier to future erosion

USACE embarks on sediment control project in Lake Pepin, Minn.
USACE embarks on sediment control project in Lake Pepin, Minn.

The U.S. Army Corps of Engineers (USACE) proposed a pilot project to use sediment dredged from the Mississippi River to build several islands near the head of Lake Pepin in Lake City, Minn. The project will aim to restore wildlife habitat and address island erosion while finding a new use for dredged sediment.

According to the Minnesota Public Radio, the idea has been has been in the works for several years since a local nonprofit, Lake Pepin Legacy Alliance, pitched the idea to the Corps St. Paul district.

"The communities at the upper end of the lake, where the sediment is really filling in and creating really shallow depths, have been increasingly cut off from the lake," said Rylee Main, executive director of the Lake Pepin Legacy Alliance.

The island creation project is part of a larger effort to increase wildlife, restore floodplain forests and create more depth in Lake Pepin, Main told Minnesota Public Radio. The project will use up to 500,000 cu yards of dredged sediment to create islands on top of previously eroded islands; however, because USACE dredges the Mississippi River every year, there remains a large portion of unused sediment. In the Lower Pool 4 near Wabasha, Minn., alone, USACE dredges 250,000 cu yards of sediment annually.

In addition to fixing eroded islands and finding a home for dredged sediment, the islands also will help slow wave and wind energy, preventing sand and sediment from becoming suspended in the river.

The final design will be finished by April 2020 and will be followed by a review period. Construction is expected to begin in 2021, if the design is approved, reports the Associated Press. With an estimated price tag of $10 million to $20 million, the Wisconsin Department of Natural Resources as well as local cities and private donations are expected to help fund the sediment control project.