North Fork of the Zumbro River


Wabasha County, MN







Construction Materials Testing & Inspection

Environmental Compliance

GIS Services

Grants & Funding

Natural Resources

Project Management & Construction Administration

Public Engagement


Vibration Monitoring

Water Resources

WSB recently worked with the Wabasha Soil and Water Conservation District (Wabasha SWCD) in Wabasha County, MN, to remove remnants of an old dam and restore the North Fork of the Zumbro River. The project required restoring an eroded bank of the river and mitigating habitat loss.

The Zumbro River winds through southeastern Minnesota to the Mississippi River and is highly susceptible to bank erosion. The river was dammed in the early 1900s and the blockage stopped the North Fork channel from flowing. When the main dam was later removed, there were remnants of the dam on each side of the channel that needed to be removed. Additionally, the remnants blocked the river from flowing downstream when flooding or extreme weather events occurred. One of the banks had eroded while the North Fork was dammed, which created a nearly vertical drop from the top of the bank down to the water. The erosion created nutrient loading in the channel which reduced water quality within the river.

To restore the channel and alleviate nutrient loading and habitat loss, we fixed the eroded bank, removed remnants of the dam and then recreated a riffle structure for fish populations to provide a food source.

Stream and river restoration is important so that people, animals and other species can use the channel for a variety of purposes. Restoration is typically carried out to improve water quality in a channel, mitigate habitat loss and improve the public’s ability to use the channel for fishing and other recreational activities.

The first step in restoring the channel was a pre-construction survey to determine the desirable slope of the eroded bank and where to place the riffle structure. Erosion causes additional nutrient loading to the river, and then these nutrients run downstream, impacting water quality. Next, in the design phase, WSB designed a stable slope for the eroded bank, so the public could walk down the bank to the water. The design of the slope ensured that, in the event of flooding, the North Fork would not experience mass erosion.

The dam remnants posed an interesting challenge for the project team. The City of Mazeppa wanted to reshape the remnants so that they did not block the flow without creating a disturbance for landowners around the project site. Typically, heavy drilling is required to remove concrete that creates significant noise and vibration to the surrounding areas. We pivoted and utilized an expansive mortar to break the existing concrete structure so that it could be removed with minimally invasive methods. This change decreased noise and vibration during the reshaping. We also used vibration monitoring equipment to assess vibration during structure removal.

Partnerships played a large role in the success of this project. We worked with local Soil and Water Conservation District, the Minnesota Department of Natural Resources, the Army Corp of Engineers, adjacent landowners and the City of Mazeppa to obtain permits for the project. Once the project was permitted, we performed construction oversight and public engagement, including leading a public meeting during COVID that was attended both in-person and virtually by stakeholders in the local community.

Following project completion, the North Fork of the Zumbro River now offers fishing easements and recreational opportunities. The restoration project resulted in an improved habitat for people, animals, fish populations not only at the project site, but further downstream as well.

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