Holter Dam facts for kids
Quick facts for kids Holter Dam |
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Holter Dam in 1918
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| Official name | Holter Dam |
| Location | Lewis and Clark County, Montana, U.S. |
| Coordinates | 46°59′30″N 112°00′21″W / 46.99167°N 112.00583°W |
| Construction began | 1908 |
| Opening date | 1918 |
| Operator(s) | NorthWestern Corporation |
| Dam and spillways | |
| Impounds | Missouri River |
| Height | 124 feet (38 m) |
| Length | 1,364 feet (416 m) |
| Reservoir | |
| Creates | Holter Lake |
| Power station | |
| Installed capacity | 50 MW |
| Annual generation | 319,800,000 KWh (2009) |
The Holter Dam is a big dam on the Missouri River in Montana, United States. It's about 45 miles (72 km) northeast of Helena, Montana. This dam is special because it makes electricity from the river's flow.
Built between 1908 and 1918, the dam is 1,364 feet (416 m) long and 124 feet (38 m) high. It creates a large body of water called Holter Lake, which is also known as Holter Reservoir. This lake stretches for 25 miles (40 km) and can hold a huge amount of water. Holter Dam is a "run-of-the-river" dam. This means it can make electricity using the natural flow of the river, without needing to store extra water.
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Building Holter Dam and Lake
The Story of Holter Dam
Holter Dam was built by two companies: the United Missouri River Power Company and the Montana Power Company. The idea for the dam came from Samuel Thomas Hauser. He was a former governor of Montana and wanted to build dams to create electricity.
In 1906, Hauser planned a dam at this spot to provide power for a large mining company. The dam was named after Anton Holter, who was a director of the power company. A famous engineer named John Ripley Freeman designed the dam. He also worked on other big projects like the Panama Canal.
Building the dam was tough. There were many unexpected costs. Also, another dam built by Hauser's company, Hauser Dam, had failed earlier. This made investors nervous. Construction on Holter Dam stopped in 1910.
Later, Samuel Hauser sold his part of the company to John D. Ryan. Ryan then combined several power companies to form the Montana Power Company in 1912. Montana Power took over the unfinished Holter Dam.
Construction started again in 1916. The dam was needed to power new railroads. Over 500 people worked on the project. They even built a large camp with more than 115 buildings. This camp had dorms, homes, a dining hall, a school, and even a hospital!
Holter Dam was finished and started making electricity in 1918. It was the sixth and last dam built by the company in that decade. When it was completed, Holter Dam was the tallest hydroelectric dam on the Missouri River.
The dam has four powerful water turbines that spin to make electricity. It can generate 40,000 kilowatts of power. The dam also has special "flashboard" gates. These allow water to flow over the top when the lake is very full.
Today, Holter Dam is still an important historic site. Its powerhouse and old construction camp show how hydroelectric power was developed in Montana.
Holter Lake: The Reservoir
When Holter Dam was built, it raised the water level by about 100 feet (30 m). This created Holter Lake, which is about 24-mile (39 km) long. The lake covers an area of 4,800 acres (1,900 ha).
Holter Lake is about 50 feet (15 m) deep on average, but it can be as deep as 121 feet (37 m). It holds a massive 243,000 acre-feet (300,000,000 m3) of water when full.
The Missouri River flows freely for 90 miles (140 km) between Holter Dam and the five dams located at Great Falls, Montana.
Nature Around Holter Dam
Gates of the Mountains
Holter Lake has two main parts: upper and lower. In the middle, there's a narrow, 5-mile (8.0 km) section called the Gates of the Mountains. This area is famous for its tall, steep rock walls.
The Lewis and Clark Expedition first saw these amazing cliffs in 1805. Meriwether Lewis wrote that the cliffs rose "perpendicularly to the height of 1200 feet." He called it "the gates of the rocky mountains."
Before the dam, the Missouri River flowed very fast through the Gates of the Mountains. Now, Holter Dam has slowed the water down a lot. The water level in the Gates is now about 14 feet (4.3 m) higher than it was in 1805. This area has been a popular tourist spot for over 100 years.
Mann Gulch
Between the two parts of Holter Lake, near the Gates of the Mountains, is a place called Mann Gulch. This gulch was the site of a terrible fire in 1949. Thirteen smokejumpers, who are firefighters who parachute into remote areas, lost their lives there. This sad event was written about in the book Young Men and Fire. Today, people usually visit Mann Gulch by boat.
How Holter Dam Works
As of 2010, Holter Dam can make 50 megawatts of electricity. The amount of water flowing through the dam is usually controlled by the Canyon Ferry Dam upstream.
In 1972, the dam's wooden flashboards were replaced. In 1984, the dam stopped making electricity for a short time. This happened after a forest fire damaged a power line.
In 1999, the Montana Power Company planned to lower Holter Lake's water level to fix the flashboards. Many people were upset about this. So, the company found a new way to do the repairs. They used special steel "cofferdams" to drain water only around the flashboards. This allowed repairs without lowering the whole lake.
In 1999, Montana Power sold all its dams, including Holter Dam, to a company called PPL, Inc. Later, in 2014, PPL sold Holter Dam and its other Montana dams to NorthWestern Corporation.
For many years, people could walk across the top of Holter Dam. This made it easy to get to both sides of the river. However, after the September 11 attacks, the dam was closed to the public for safety reasons.
Holter Dam is known for being very good at making electricity. It's also considered an important historical engineering site in Montana.
Fun Activities and Fish in Holter Lake
Today, Holter Dam and Holter Lake are very popular places for outdoor fun. People love to go boating, fishing, hiking, and camping here.
Fishing in Holter Lake
Just below Holter Dam, the Missouri River is famous for its "Blue Ribbon" trout fishing. This means it's one of the best places to catch trout. It's common to catch 5 pounds (2.3 kg) rainbow trout here, and some have even been over 10 pounds (4.5 kg)! Most fish are 18 inches (460 mm) or longer. There are many more rainbow trout than brown trout in this area.
In Holter Lake itself, rainbow trout weighing 3 pounds (1.4 kg) are often caught. Other fish like burbot and stonecats also live below the dam. In the past, kokanee salmon and yellow perch were common, but their numbers have gone down.
Holter Lake has always been known for having many different types of fish. Besides trout, you can find kokanee salmon, walleye, and yellow perch. To protect the fish, special rules have been put in place. For example, in 1992, rules were made for brown trout. You could only catch them and then release them back into the water.
Managing the Fish Population
Managing the dam and lake is important for the fish. In 1996, a fish disease called "whirling disease" was found in the Missouri River below Holter Dam. Also, more and more people started fishing in the river below the dam. To help the fish, state wildlife managers set limits on how many rainbow trout could be caught.
In 1997, the dam's owners had to create new rules for how the dam should be run. These rules make sure the dam keeps operating as a "run-of-the-river" dam. They also require keeping the water levels behind the dam within a certain range. This helps protect the fish and wildlife.
Sometimes, droughts (when there's not enough rain) affect the dam's operation. In dry years, less water flows over the dam. This can impact the fish. For example, in 2004, low water flows and whirling disease caused a drop in the number of large fish below the dam.
Wildlife experts also worry about walleye fish. Walleye are predators that eat small trout and yellow perch. They sometimes wash over the dam into the trout fishing areas. To protect the trout, rules were made to allow unlimited walleye fishing in some areas. This encourages people to remove them.
Another fish that causes problems in Holter Lake is the northern pike. These fish eat other desirable native species. To control them, the state removed all fishing limits on northern pike in certain areas. They also started a project to remove pike from the Missouri River and its feeder streams.
In 2011, the state set new limits for trout fishing below Holter Dam. This was to help the trout population grow. And it worked! In 2011, the number of rainbow trout in the river below the dam was very high, one of the highest ever recorded.
Wildlife and Recreation
Holter Lake is a truly amazing place. It's surrounded by beautiful natural areas like the Beartooth Wildlife Management Area and the Gates of the Mountains Wilderness.
Many animals live here, including bald eagles, bighorn sheep, elk, falcons, golden eagles, hawks, mountain goats, osprey, and pelicans. Meriwether Lewis even discovered a new bird, Lewis's woodpecker, nearby. You can often see birds of prey catching fish from the lake and river.
There are also boat tours that take visitors through the stunning Gates of the Mountains. The Bureau of Land Management (BLM) manages the public lands around the lake. They have four campgrounds at Holter Lake for people to enjoy.
Conservation projects are also happening at Holter. For example, money has been donated to restore plants along the Missouri River below the dam. This helps keep the water cool, which is good for the trout. Studies are also being done on fish habits to help manage the lake's ecosystem.
Images for kids
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Interior of the Holter Dam powerhouse in 1994. Generating turbine No. 1 is in the foreground.
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Lewis' woodpecker, a bird first identified near where Holter Dam is located today.
