On Tuesday night, the 53-year-old Upper St. Anthony Falls Lock and Dam in Minneapolis will run its final cycle.
MPR News reports that, by congressional decree, the lock and dam will close in a precautionary step to block the continued migration of invasive carp in the Mississippi River. The destructive species has been encroaching into territory along the river for decades, but have not made it past Minneapolis to invade the upper Mississippi.
It will mark the first time a navigable waterway has been closed to navigation in an effort to stop the advancement of an invasive species. U.S. Rep. Keith Ellison and Sen. Amy Klobuchar pushed for the lock's closure in federal water legislation.
The Star Tribune published a story when the year's first commercial barge arrived in April, noting it would be the last shipping season before the congressional mandate would close the upper lock.
It remains unclear if the plan will work, and what long-term effects of the lock's closing will have on the river.
MinnPost noted the Army Corps of Engineers will keep the facility functioning but only for flood control, which has been required six times in the life of the structure.
The story added that during the next two weeks, a set of steel bulkheads will be lowered in slots upstream to protect the gates. The lower gates will be left open and the water level inside the lock will remain at the level of the river below the falls.
It's unclear what will happen to the facility after the lock is closed to navigation, but the MinnPost story suggests the Minneapolis Park Board and partners such as the Corps and the National Park Service "have a chance to do something dramatic with the property," which could include transforming the building adjacent to the lock into a visitor center with a restaurant that would overlook the river.
In 1937, Congress passed the Upper Minneapolis Harbor Development Project that allowed for the construction of the Upper St. Anthony Falls lock and dam. The project was completed in 1963.