New Mississippi River island to protect Hastings MN Lock and Dam

Work is underway to build a new island in the Mississippi River near Hastings, a $10 million project aimed at preserving the lock-and-dam system that allows some 10 million tons of goods to be shipped along the river every year.

The human-made, arrowhead-shaped island represents a unique project on the Upper Mississippi, according to the U.S. Army Corps of Engineers.

“It’s really exciting for the team to see this being constructed,” said Nick Castellane, a project manager with the U.S. Army Corps of Engineers. “We’ve been working on it for a number of years.”

About seven years ago, planning began on the project, due to longtime erosion along the embankment near the pool of water of Lock and Dam No. 2. The embankment itself was built with the portion of the dam in the 1930s.

As Castellane tells it, the size of Pool No. 2 allows for two miles of “wind fetch,” with wind building up speed across the water, causing waves to batter the embankment. Crashing ice every spring as the river clears also contributes to erosion along the embankment.

Modeling from the Army Corps engineer team shows that the new island should provide some shield for the embankment from those external factors.

If not for the island, the embankment would continue to erode, Castellane said, and once enough erosion occurred, the river could overflow its banks and reduce water levels in that portion of the lock-and-dam system, impacting barge navigation and recreational boating.

Long-term solution

During the planning stages, three ideas emerged. The Army Corps could pile heavy rock — “rip rap” — on the embankment, spending $1 million or so every three to five years and in the hope that it would hold off additional erosion.

Or construction crews could try to build out the embankment edge, creating a larger buffer, but that plan would impact waterflow patterns.

Planners felt both of those plans seemed to only provide temporary fixes, and the island emerged as a more long-term solution, expected to have more than a 50-year lifespan.

The locks and dams were installed nearly a century ago on the Upper Mississippi River so that boats hauling freight up and down the river could have easier passage.

How does the lock-and-dam system work? The upper river is divided into sections called pools, where a fixed amount of river is held back by a dam. This system creates a minimum 9-foot channel in the Upper Mississippi River. Each corresponding lock acts like a water elevator, bringing boats up or down to the water level of the next pool. Another analogy would be a staircase of water that boats and barges climb and descend.

Native ecosystem