|Highways, Byways, And Bridge Photography|
Saint Louis River Water Project
||• Structure ID:
||River Mile 29.2
||• Structure Type:
||Earth Embankment w/Concrete Gravity Structure
||• Structure Width:
||1,600 Foot Main Structure, 473 Foot Wide Spillway
||• River Elevation (Pool):
||• River Elevation (Outflow):
||• Water Fall:
||• Hydro Power:
||• Date Built:
The Thomson Water Project consists of a number of components located in
and around Thomson, Minnesota, and the nearby Jay Cooke State Park. The
dam features a remote power house that is 3 miles from the main dam.
The project begins with the main dam structure near the Saint Louis River
bridge on MN-210. Water flows out of this structure and into the historic
Saint Louis River channel. Water also backs up behind the dam forming Thomson
Reservoir, which is about one square mile in size. A second dam structure
and gate house allows water to flow into Forbay Canal. That 2 mile long
canal feeds into a mile long set of underground pipes, which carry the
water to the power plant. While the power plant is 3 miles from the dam,
the river channel takes a bit over 5 miles to reach the power plant.
While most visitors see only the dam structure near the Saint Louis River
channel, the dam is actually composed of many smaller dam segments. Some
of these segments have been rebuilt and merged over the years. Here is a
current listing from the National Dam Inventory:
|MN83020||Thomson Dam No 1-1/2
|MN83021||Thomson Dam No 2A, 2B
|MN83022||Thomson Dam No 2-1/2
|MN83023||Thomson Dam No 3, 2-3/4, 3, 3A, 4, 4A
|MN83024||Thomson Dam No 5
|MN83025||Thomson Dam No 5-1/2
|MN83026||Thomson Dam No 6
|MN83027||Thomson Dam No 8
|MN83028||Thomson Dam No 9
|MN83029||Thomson Dam No 10
|MN83030||Thomson Dam No 11, 11-1/2, Gate House
|MN83031||Thomson Dam No 12
The Thomson Water Project was built by Great Northern Power in 1907.
Great Northern Power was an operating division of the Great Northern
Railroad. It was later transferred to the Saint Louis Power Company.
Today, it is known as the Thomson Energy Center, which is owned by
Minnesota Power, which is a division of Allete, Inc.
A storm of historic proportions hit the Duluth area on June 19-20, 2012,
dropping 11 inches of rain in some areas. The Thomson Dam overtopped
causing extensive flooding in the city of Thomson. Large amounts of debris
fouled the gates at the gate house and intake house resulting in extensive
damage to the structures. The power plant flooded causing a need to shut
down the turbines, and the water damaged much of the electrical equipment.
Later, the south wall of the Forbay Canal failed, causing the lake to
drain cutting a new river channel through Jay Cooke State Park. This
resulted in a long section of highway MN-210 washing out. In addition,
MN-210 was washed out near the Fond du Lac Dam and in front of the
Thomson Dam. It took two years of work to bring the first generator
back on line (unit #6), and considerable work remains to be completed
as this update was written in late 2015.
The photo above is looking north towards the older dam spillway and gates
located towards the west end of the main dam control structure. This vantage
point at the west end of the highway MN-210 bridge is perhaps the best view of
the dam, showing the cascades over the rocks just downstream of the dam.
The photo above is looking north towards the control gates at the Thomson
Dam, as seen from the Kayak and Canoe Institute Outpost parking lot. The
photo below is a close view of a channel that was blasted through the rock
back in the logging era. Remains of some type of structure is located just
to the left of this channel.
The photo above is the larger group of control gates located on the east
end of the main dam structure. There is no good clear view of these gates
due to the large rock formation located just downstream, as seen in the
photo below. The channel through these rocks was also blasted, and again,
we see some logging era foundations just to the right of the channel.
The photo above is the eastern section of the main dam control structure as
seen from highway MN-210. The photo below is a small falls where water
flowing through the dam collects into a channel before passing under the
highway MN-210 bridge over the Saint Louis River.
These two photos are views of one of the longer of the concrete walls that
fill gaps between rocks along the south side of the reservoir. The photo
above is the front of the dam, while the photo below is the back side of
the dam. The railings are to discourage people from walking across the
dam. The water is at least 20 feet deep, and the front side is a stagnant
pool covered with algae.
The photo above shows three more similar concrete dams filling gaps between
the rocks. These structures are located just east of the UMD Outpost pier,
which is just east of the main control structure. The photo below is a
small inlet between the rocks at the leading edge of the reservoir.
The photo above is looking east from the UMD Outpost pier. The rocks to the
right are the south wall of the reservoir, while the rocks to the left are
part of a chain of islands running towards the east end of the reservoir.
The photo below is a view of the rocks along the trail leading from the UMD
Outpost to the pier at the canoe landing.
An unusually powerful storm dropped a foot of snow across northern Minnesota
in late October, 2010. The temperature rose just after the storm, resulting
in that snow melting very quickly. Much of the snowmelt ended up in the
Saint Louis River, resulting in a spectacular water show downstream of the
Thomson Dam. These two photos, and the ten that follow are from October 30,
2010. The photo above is the western section of the main dam control
structure as seen from a ridge just west of the river. The photo below is the
same section of the dam as seen from the west end of the MN-210 Bridge over
the Saint Louis River.
These two photos are closer views of two sections on the western end of
the main dam control structure. The photo above shows one of the spillway
gates open, allowing a 36-foot wide torrent of water to pass over the dam
and into a normally dry area in front of the dam. The photo below shows
the series of three smaller dam gates. These gates are typically the only
gates to be used during normal river flow levels.
The photo above is some maintenance equipment that is parked at the east
end of the main dam control structure. I suspect that this is part of a
late season dam maintenance project, possibly one that was scheduled when
the river flow is typically very low. The photo below is looking west
along the reservoir side of the Thomson Dam. The small building on top of
the dam is a mobile crane that is used to raise and lower the dam gates.
These two photos are the eastern end of the main dam control structure. This
5-gate structure appears to be newer than the gates on the western section
of the dam. The photo above is from an overlook at the parking lot for the
University of Minnesota Duluth Outpost. The photo below is a view from a
rock ridge on the west side of the river channel.
These two photos are views looking north towards the east end of the main
dam control structure. The photo above shows the remains of an older
water control structure from the logging era before the Thomson Dam was
built. The photo below includes faint rainbows above and below the rocks
in the center of the photo.
These two photos are views looking north from the highway MN-210 Bridge over
the Saint Louis River. The photo above shows the water flowing out of the
newer 5-gate structure as it splits and flows around both sides of a stubborn
section of 1.9-billion year old rock. The photo below is a wider view from
the same location that includes views of both the eastern and the western
sections of the main Thomson Dam control structure.
These two photos, views from the nearby Minnesota highway MN-210 bridge,
show that the water flow is back to summertime normal levels here in July
These two photos (and the two that follow) are views from the summer of
2013. With the Forbay Canal damage being repaired, the water that
normally was diverted through the canal and power plant returned to the
Saint Louis River channel. This resulted in large water flows and
spectacular views that haven't been seen in decades.
Two additional views from the summer of 2013 as the full flow of the
Saint Louis River was coming through the dam. The photos look much like
periods of high water in the spring despite this being the middle of summer.