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Zumbro River Restoration

Removing a damaged, substandard dam led to the innovative restoration of a river corridor

  • 1.05

    Mile River Channel

  • $3M

    Construction Value

  • 10

    Rock Arch Riffles

  • Oronoco, Minnesota

    Oronoco, Minnesota

Rock arch rapids and other features moderate river flow when a substandard dam is removed and natural river flow is restored.

When a flood damaged the Lake Shady dam beyond practical repair, Olmsted County saw an opportunity to return the upriver lake to a riverine, wetland, and upland bionetwork. The project needed to restore the river’s ecological health and natural beauty without impacting high water elevations during future flood events while also creating new recreational opportunities for the community.

Our design called for demolishing the existing concrete dam and constructing an 800-foot-long series of 10 rock arch rapids to withstand the tremendous stresses caused by an estimated 100-year storm event flow—approximately 2,800 cubic feet (79 cubic metres) per second. Using specially quarried four- to six-foot boulders, the arches were built under low river flow and frozen conditions to preserve the lakebed and support heavy equipment.

The project restored 1.05 miles (1.69 kilometres) of river channel with 120,000 cubic yards (91,700 cubic metres) of saturated sediment, 11 riffle structures, and 2,665 linear feet (812 metres) of woody debris structures to stabilize banks and improve fish habitat. The scenic overlook adapted from a modified dam abutment structure and a 1,100-foot (335-metre) portage way encourage a variety of encounters with this reach of the Zumbro River now restored to its natural beauty.

At a Glance

ACEC of Minnesota Engineering Excellence Awards - Grand Award, 2019
Meet Our Team

Joe Palen, Senior Associate, Community Development

We strive to provide exceptional customer service to our clients by providing trusted advice and creative, cost effective solutions.
Joe Palen Senior Associate, Community Development Read More

George Athanasakes, Vice President, Ecosystem Restoration, Environmental Services

We analyze natural processes driving ecological functions and incorporate these processes into designs to create self-sustaining ecosystems.
George Athanasakes Vice President, Ecosystem Restoration, Environmental Services Read More

Linda Brown, Senior Associate, Community Development

I work with private developers and governing entities to develop areas in communities that benefit everyone.
Linda Brown Senior Associate, Community Development Read More

John Smyth, Associate

My job is to help communities protect and restore their water resources, so they can be enjoyed for generations to come.

Joe Palen

Senior Associate, Community Development

George Athanasakes

Vice President, Ecosystem Restoration, Environmental Services

Linda Brown

Senior Associate, Community Development

John Smyth


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