The over 100-year-old Thomson Hydro Station in Jay Cooke State Park on the St. Louis River produces 72 megawatts of energy with its six turbines, enough to power Duluth and its roughly 90,000 residents. That makes it the largest hydro station in the state.
Combined with the other hydro stations, they generate up to 120 megawatts of electricity for northern Minnesota residents. The power generated is reliable, renewable and carbon-free.
That and more is what Deputy Undersecretary of the Navy Jodi Greene and other naval personnel learned Wednesday, July 17, during a tour of the Thomson Hydro Station.
Greene is the highest ranking civilian in the U.S. Navy. The visit and tour was a part of Navy Week celebrations in the Duluth area. The event began with sailors, dressed in 1812-era uniforms, who presented colors as the national anthem was sung.
Speakers including Greene, Duluth Mayor Emily Larson, Allete President Bethany Owen and Hydro Renewable Business Manager Chris Rousseau spoke during a ceremony.
Minnesota Power, a division of Allete, owns the hydro stations and hosted the event. The purpose for the visit was due in part to the station's historical military significance during both world wars, as well as their support for military employees.
The station was mostly a hydroelectric utility at the time and the main power supplier to the iron mines. Rousseau noted that several of the building's windows are still blacked out from World War II. This was done to make the building difficult for war planes to find during night raids.
Rousseau explained the station and the military have a special history.
“There was an active military presence that protected the station in World War I and protection continued in World War II,” Rousseau said. “They (hydro stations) were part of a supply chain for the steel industry, who relied on the power.” The steel would be used for military tanks, ships and airplanes.
There are five hydro stations spread among three river systems: the St. Louis, Mississippi and Kawishiwi rivers in northern and central Minnesota.
The Thomson Hydro Station is unique because it has a reservoir of water stored behind the Thomson Dam.
The 649-acre reservoir fills when demand for electricity is lower and released when the demand for power increases, typically in the morning.
While the water that generates power at the Thomson Hydro Station comes from the St. Louis River, it enters the station through huge underground pipes called pen stocks. The pipes are 7 feet in diameter and there is a 380 foot drop from top to bottom. The pipe at the Fond du Lac Hydro Station is 18 feet in diameter. More height equals more power.
There are five storage reservoirs on the St. Louis River. The one in Scanlon is set back, but can be seen easily while driving on Minnesota Highway 61 from Esko and Scanlon.
The other reservoirs are at Knife Falls and Fond du Lac, which can be seen toward the end of the scenic drive through Jay Cooke Park, ending at the village of Fond du Lac.
During the winter, Whiteface, Boulder Lake, Island Lake, Fish Lake and Rice Lake reservoirs supplement to keep electricity flowing to the surrounding areas when the St. Louis River is partially frozen.
The flood of 2012 damaged the station. It took about two years of reconstruction to get it in working condition again. The flood water level reached a record-breaking 16.5 feet when a slow-moving rainstorm moved across the area.
“Our other hydro stations were generating power during that time frame,” Allete Communications Manager Amy Rutledge said. “It’s important to note that we get our generation (used to make electricity) from a variety of sources, including hydro, wind energy, solar and our coal plants.”
Minnesota Power covers 26,000 square miles in northeastern Minnesota. It also supplies retail electric service to 145,000 customers and wholesale electric service to 16 municipalities.