Minnesota Power moves forward with flood repairs
Minnesota Power, a division of ALLETE Inc. (NYSE: ALE), said this week that it expects to have its largest hydro station, which has been out of commission due to flooding one year ago, partially back in operation by the end of this year and fully restored in 2014.
Major repairs are underway at the company's Thomson Hydro Station on the lower St. Louis River in Jay Cooke State Park. The 106-year-old hydroelectric plant has been out of service since June 2012, after as much as 10 inches of rain fell in the region, causing flash floods in some areas and longer-term flooding in others.
"The significance of this localized event was striking," said Minnesota Power Chief Operating
Officer Brad Oachs. "We saw peak river flows of 56,000 cubic feet per second which was 40
percent above previous record flows. Our employees performed admirably under extremely
While the integrity of the company's hydro dams was maintained during the unprecedented event, the sheer volume of water and speed at which the flow of the river changed flooded the six turbines at Thomson, overtopped the Thomson reservoir and breached a portion of an earthen dike at the forebay, a small reservoir that feeds water into the Thomson power station. The flood washed out roads and caused mudslides in Jay Cooke State Park, limiting access to the powerhouse by foot or on all-terrain vehicles for months.
Minnesota Power operates five reservoirs and four hydro stations along the St. Louis River: Knife
Falls, Scanlon, Thomson and Fond du Lac. The Thomson facility, capable of generating 72
megawatts, is the largest hydro facility in the state of Minnesota and an important part of the
company's EnergyForward strategy, which calls for a balanced, less carbon-intensive energy
"Thomson is the very heart of our hydro system and has served our customers with low-cost
renewable energy for more than 100 years," Oachs said. "Investing in repairs and other
improvements to strengthen the system against future flood events will position Thomson as a
reliable and cost effective emission free resource for the next 100 years."
Minnesota Power has been working closely for the past year with the Federal Energy Regulatory
Commission (FERC), the agency responsible for dam safety oversight, and an independent
consulting board of engineers on assessing impacts of the June 2012 flood, planning and design
development to restore the forebay and other improvements to the hydro system. The company has filed with FERC a comprehensive report of how its employees and systems performed during the June 2012 event.