Minnesota’s Rapidan Dam faces imminent failure after flooding breach

On Monday morning, June 24, 2024, flooding on the Blue Earth River breached the Rapidan Dam, prompting officials to declare an “imminent failure condition.” This followed debris accumulation identified on June 23, which led to emergency measures in North Mankato, including road closures and levee construction, with potential downstream impacts predicted to raise river levels by 15 to 60 cm (6 inches to 2 feet) toward Mankato.

On June 23, 2024, Blue Earth County Emergency Management in Minnesota identified a significant accumulation of debris at Rapidan Dam, prompting immediate monitoring by Public Works, Emergency Management, and the Sheriff’s Office.

The dam faced imminent failure conditions due to the debris, which included contributions from Xcel Energy and County infrastructure. This situation led to power outages and the potential for road closures, specifically on County Road 33 bridge and County Road 90 bridge, which were closely monitored for debris passing downstream.

On June 24, the City of North Mankato declared a flood emergency, initiating the construction of a temporary earth wall levee at the intersection of Lookout Drive and Lee Boulevard. The intersection was closed to facilitate these efforts, aimed at protecting the city from the potential failure of Rapidan Dam. The rising river levels were closely monitored, with the levee built to a height of 10.5 m (34.6 feet) as a precaution.

City officials assured residents that no evacuations were necessary at this time but urged them to stay informed via the city’s communication channels.

The current river level stood at 8.5 m (28 feet), with the levee system designed to handle up to 12 m (39.5 feet). Engineers on-site predicted that a failure of the dam could result in an increase of 15 to 60 cm (6 inches to 2 feet) in river levels downstream.

As a precautionary measure, Xcel Energy deployed 170 employees and 400 pieces of equipment to protect the nearby substation at Sibley Park, with the MSU campus serving as a staging area. Continuous updates were provided to city officials, including Mayor Najwa Massad, who met with Senator Amy Klobuchar and Representative Brad Finstad to discuss the situation.

The city implemented the Rapidan Dam Emergency Action Plan, which included continuous patrols and monitoring of the levee and flood control systems, staffing the Water Resource Recovery Facility (WRRF) 24/7, and ensuring that pump stations were operational. Parks such as Land of Memories Park, Kiwanis Recreation Area, and parts of Sibley Park were closed due to flooding.

Residents were advised to avoid closed areas and follow travel advisories due to road closures. For any flood-related inquiries, residents were directed to contact the Emergency Operations Center at 507-387-8788. The situation remains under close observation, with authorities prepared to take further action as necessary.

The Blue Earth River begins in northern Iowa and flows 174 km (108 miles) north through southern Minnesota, passing cities like Blue Earth, Winnebago, and Vernon Center before entering the Minnesota River at Mankato. The watershed includes 21 cities, with Mankato and Fairmont being the largest.

Blue Earth County officials told WCCO the dam was recently inspected and was in good shape before the rainfall, saying the partial failure is a result of high water and debris hitting the dam.

A press conference was scheduled for 09:00 LT on Tuesday, June 25 to share more information about the situation.

References:

¹ Updates on Rapidan Dam situation – City of Mankato, Minnesota Government

² Rapidan Dam in southern Minnesota experiences partial failure; no plans for mass evacuation – WCCO – June 24, 2024

Teo Blašković

I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.

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