Most dams have the power plant attached to the dam structure, with
water moving through the dam turning the hydro generators and then
exiting back into the river channel. The Thomson Water Project is
built quite different from this traditional dam style. On the Thomson
project, a dam holds back a large reservoir of water. The dam also
allows some water to flow down the historic river channel. The water
for the power plant actually flows out of an head structure and
along a 2 mile canal to reach this intake facility. From here, water
flows another mile through underground pipes to reach the powerplant.
Once the water runs through the power plant, it is returned to the
St. Louis River at an elevation that is 370 below the dam at the top
of the bluffs. In comparison, the 370 foot water fall is about half
the 726 foot height of Hoover Dam.
The intake structure is located at the intersection of MN-210 and
Jay Cooke Road inside the Jay Cooke State Park. The Thomson Canal
brings water in from the Thomson Reservoir. The intake structure
accepts the water from the canal, regulates it using giant valves,
and then channels the water into 3 large pipes. These pipes flow
down the hill to the power plant area.