MANKATO, MN — The Rapidan Dam near Mankato, Minnesota, is on the brink of failure following severe flooding of the Blue Earth River. Officials have issued urgent warnings about the dam’s “imminent failure condition,” causing alarm among residents and authorities.

The Blue Earth County Sheriff’s Office has reported that the river, swollen by recent heavy rains, has eroded the sides of the dam and accumulated significant debris. This has led to the declaration of an imminent failure status, with warnings issued to those downstream. “We do not know if it will totally fail or if it will remain in place,” the sheriff’s office stated, emphasizing the necessity of alerting residents and relevant agencies.

The dam, a crucial infrastructure piece located outside the city of Mankato and about 85 miles southwest of Minneapolis, faces unprecedented pressure. An Xcel Energy substation at the dam, providing power to approximately 600 customers, was washed away early Monday morning. Xcel Energy is currently working with local authorities to replace the destroyed substation and restore power.

Governor Tim Walz addressed the situation at a press conference on Monday morning, noting that the state has been inundated with roughly 18 inches of rain in recent weeks. This deluge has saturated the ground and left the water with nowhere else to go, exacerbating the flooding crisis. “With that being said, the resources that are being deployed are strategically out there,” Walz said. “We’re making sure, first and foremost, people are safe, protecting property, and protecting public infrastructure.”

Flooding has impacted approximately 40 counties, with some already declaring a state of emergency. Governor Walz indicated that a request for a presidential disaster declaration might be forthcoming if the damage assessment meets federal assistance thresholds.

The Rapidan Dam, built in 1910, has suffered repeated flooding over its more than a century of operation, causing significant structural damage. A 2021 assessment highlighted the need for either major repairs or a complete rebuild of the dam, both of which would be costly and time-consuming endeavors. Repairing the dam is estimated to take four years, with three years dedicated to planning and design, while constructing a new dam could take up to ten years, including removal and river restoration.

The dam’s ability to provide hydroelectricity has been significantly hampered by the ongoing damage. Last year, Blue Earth County began the process to relinquish its licensure exemption under the Federal Energy Regulatory Commission (FERC). If approved, this would place the dam under the control of the Minnesota Department of Natural Resources. “No changes to the dam structure are being proposed at this time,” the county clarified, adding that surrendering the exemption would mean that FERC would no longer have regulatory authority over the dam.


As of now, the integrity of the dam is holding, but officials continue to closely monitor the situation. The potential failure of the Rapidan Dam poses a significant threat to downstream communities, and the situation remains fluid as authorities work tirelessly to manage the crisis.

Residents are urged to stay informed through official channels and be prepared for potential evacuation orders. The situation at the Rapidan Dam is critical, and the safety of the community is the highest priority as officials and emergency services respond to this developing emergency.

Source: NBC

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