Mio Dam facts for kids
Quick facts for kids Mio Dam |
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Mio Dam Tailwater 2020
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 Location within the state of Michigan
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| Location | Mio, Oscoda County, Michigan |
| Coordinates | 44°39′40″N 84°07′54″W / 44.661143°N 84.131697°W |
| Opening date | 1916 |
| Owner(s) | Consumers Energy |
| Dam and spillways | |
| Type of dam | Embankment |
| Spillways | 1 |
| Power station | |
| Turbines | Allis Chalmers |
| Installed capacity | 4.96 MW |
The Mio Dam is a special kind of wall built across the Au Sable River in Michigan. It's a hydroelectric dam, which means it uses the power of flowing water to create electricity. The Mio Dam can make 4.96 megawatts (MW) of electricity, enough to power many homes!
This dam was the fourth of six dams built by a company called Consumers Power (now Consumers Energy) between 1906 and 1924 along the Au Sable River. It's the one furthest upstream, meaning it's the first dam you'd reach if you traveled up the river. The Mio Dam was finished in 1916.
The Mio Hydroelectric Plant has a strong dirt wall (called an embankment) on each side. These walls are connected by a spillway, which is like a giant drain for extra water. The powerhouse, where the electricity is made, is located north of the spillway. There's also an outdoor substation that helps send the electricity out.
If you want to visit, Consumers Energy provides a boat ramp for public access to Mio Pond. There are also special paths and slides for canoes and kayaks to get around the dam safely. Even though it's over 100 years old, the Mio Dam still uses the same turbines and generators that were put in when it was first built!
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Why Mio Dam is Special
The Mio Dam is important for several reasons, from protecting nature to its unique design and role in a famous canoe race.
A Wild and Scenic River Area
In 1984, the United States government named a 23-mile part of the river below the Mio Dam as a "National Wild and Scenic River." This means it's a very special area that needs to be protected.
This unique stretch of river, between the Mio Dam and the Alcona Dam, is home to amazing wildlife. You might see bald eagles flying overhead or the rare Kirtland’s warbler, a small bird that needs special care. It's also a great place for outdoor activities like hiking, camping, fishing, canoeing, picnicking, and watching birds.
Michigan Historic Site Recognition
In 2005, the Mio Dam was recognized as a Michigan Historic Site. This was because it was the very first hydroelectric dam to send extra river water through special tunnels built under the powerhouse. This design is called an "under-sluice" or "conduit spillway."
Normally, dams have big gates above ground to release extra water, which can be expensive. The Mio Dam's clever design saved money and helped prevent the riverbed from wearing away too much downstream. It also stopped ice from building up on the gates in winter. Even though it had this unique design, the dam was updated in 1988 to meet new safety rules. Now, it also has an extra concrete spillway above ground for when the water level gets very high.
Hydro Hall of Fame Award
The Mio Dam's smart design was celebrated in June 2017 when it was added to the Hydro Hall of Fame by HydroVision International. This award recognized how clever its original design was and how much value the dam has provided for over 100 years. The unique under-sluice design was so good that it was even used in other dams built by Consumers Power Company, like the Alcona Dam.
Au Sable Canoe Marathon
The Mio Dam is also a key spot in the famous Au Sable River Canoe Marathon. This is a challenging 120-mile overnight canoe race that happens every summer. Race teams have to carry their canoes around six dams, and the Mio Dam is one of them!
How Mio Dam Works
The Mio Dam is an earth embankment dam, which means it's mostly made of compacted earth. It has a strong concrete wall inside that helps hold back the water. This creates a "head" of 29 feet of water, which is the difference in height between the water level above and below the dam.
The original equipment from over 100 years ago is still working today! This includes two large vertical turbines and two generators, all made by Allis-Chalmers. Each generator can produce 2,500 kilowatts (KW) of power. The powerhouse building, where these machines are, is a brick building with a flat roof.
When the dam was built, it was in a very remote area, far from any train tracks. This made it hard to bring in heavy supplies like concrete, steel, and machinery that weighed more than 30 tons. Everything had to be pulled by horse-drawn wagons for many miles!
The narrow space in the river channel also led to the invention of the "conduit spillway" design. This clever idea was patented by William W. Tefft, who later became the Chief Engineer for Consumers Power Company. This spillway used two large 60-inch steel tubes to send water under the powerhouse. The dam also has one smaller concrete spillway with a single gate.
Keeping the River Cool
Consumers Energy, the company that owns and runs the Mio Dam, installed a special system in 2009 to help keep the river water cool on hot days. This was part of an agreement with groups that work to protect nature. They wanted to make the river a better home for fish and other water creatures downstream.
Studies showed that some fish, like trout, get stressed when the water gets too warm. The system at Mio Dam uses underwater air bubbles to lift colder water from the bottom of the pond up to the intake pipes for the turbines. This mixes the water and helps cool it down. Consumers Energy's operating license requires the water to be 68 degrees Fahrenheit or cooler. When temperatures rise, they turn on the air compressors, usually for about 6 hours a day, to copy how the river cools down at night. Sometimes, they run it for up to 24 hours a day at Mio.
River Flow and Safety
Since the mid-1960s, the Mio Dam has operated as a run-of-the-river hydroelectricity dam. This means that the amount of water flowing out of the dam downstream is almost the same as the amount of water flowing into the dam's pond upstream.
Automatic systems have been added to the generators. These systems automatically adjust how the dam works to keep the water level above the dam steady at 29 feet. This helps maintain the "run-of-river" flow through the powerhouse.
Consumers Energy constantly checks water flows and temperatures to make sure the dams are operating safely. They can also release extra water in a controlled way if needed. The United States Geological Survey (USGS) also has six real-time water-level gauges on the Au Sable River. These gauges send information about water levels, flow speed, temperature, and water quality to the National Weather Service. One of these important gauges is located right at the Mio Dam.
Safety is a top priority for dams. Local emergency teams regularly practice and have plans ready for any unusual situations. They work together to ensure everyone knows what to do if there's a serious problem with a dam.
