The Most Snake-Infested Rivers in Montana

Written by Jennifer Geer
Updated: September 5, 2023
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Here are the most snake-infested rivers in Montana.

Unlike other parts of the country, Montana has relatively few species of native snakes. Although ten snakes live within the state’s borders, only one, the prairie rattlesnake, also known as the western rattlesnake (Crotalis viridis), is venomous. 

10 Species of Snakes Found In Montana

The following ten species of snakes call Montana home:

Are There Water Snakes Found In Montana Rivers?

A plains garter snake, back with horizontal stripes ( one of each, visible) of orange and red running the length of its body, slithering through long grass

Plains garter snakes, found in Montana rivers, are strong swimmers.

©Alyssa Metro/Shutterstock.com

Water snakes are commonly found in the southern and eastern parts of the United States. Additionally, a few species live in the Midwest and California. However, there are no true water snakes native to Montana.

Although Montana does not have water snakes, some species in the state live near bodies of water and can be found swimming in them as well. These snakes are called semi-aquatic.

Semi-aquatic snakes in Montana are the garter snakes, and these include:

  • Common Garter Snake
  • Plains Garter Snake
  • Terrestrial Garter Snake

Semi-aquatic snakes aren’t the only species of snake you may encounter in rivers. All snakes can swim, even if they aren’t water snakes or semi-aquatic.

Read on to find out about the most snake-infested rivers in Montana.

The 5 Most Snake-Infested Rivers in Montana

Although there are no water snakes in Montana, numerous snake species live near rivers and sometimes can be found swimming in them. Here are five snake-infested rivers in Montana.

1: The Missouri River

City lights of Great Falls, Montana over the Missouri River.

The Missouri River is the longest river in North America and the fourth longest in the world.

©Shane N. Cotee/Shutterstock.com

The Missouri River is the longest river in the United States. It flows over 2,500 miles from its source in the Rocky Mountains of Montana to where it meets up with the Mississippi River in St. Louis, MO. Many different species of snakes are found along the southern portions of the river as it flows through Kansas and Missouri. But in Montana, you are most likely to spot one of the state’s three species of garter snakes in or around the river.

You may also encounter Montana’s only venomous snake species, the prairie rattlesnake. Sightings of the rattlesnake have been reported near Great Falls, MT, near the Missouri River. Additionally, a reporter for the Great Falls Tribune noticed a gopher snake, Montana’s largest snake species, basking in the early morning sun on the side of a jogging trail.

2: The Yellowstone River

Yellowstone National Park, Yellowstone River

The venomous prairie rattlesnake can be found around the Yellowstone River.

©iStock.com/samuel howell

The Yellowstone River originates in Wyoming, flows into southern and eastern Montana, and ends in North Dakota. The snakes you might come upon along its banks or swimming in the water include northern rubber boas, bullsnakes, common garter snakes, terrestrial garter snakes, and eastern racers.

According to a report, a prairie rattlesnake was found in Paradise Valley, along the Yellowstone River. And in an extremely rare occurrence, a woman walked into an apartment in Livingston, MT, to find a rattlesnake camped out on the kitchen table. Livingston is a small town that rests on the banks of the Yellowstone River.

3: Clark Fork River

clark fork river near st. regis montana

Clark Fork River originates in the Rocky Mountains and flows through Montana, ending in northern Idaho.

©md hess/Shutterstock.com

The Clark Fork River is one of the longest rivers in Montana, and the largest by volume. The river begins in the Rocky Mountains in Montana, flowing through the western part of the state and ending in northern Idaho. Snake species you may find in and around the river include the common garter snake, terrestrial garter snake, bullsnake, racer, rubber boa, and prairie rattlesnake.

Residents sometimes mistake bullsnakes for rattlesnakes, according to The Missoulian. Although the prairie rattlesnake also lives in the region, it’s sighted much less frequently.

Racer snakes live near the Clark Fork River as well. Racers are fast and agile and can speed away as quickly as 3.5 miles per hour. They often live near water and can sometimes be heard rustling through the grass along hiking trails.

Occasionally you can spot a rare rubber boa hiding under rocks or logs. This unique snake looks and feels like rubber. The small boa is mostly active at night, rarely making an appearance during the day. However, there are sometimes reports of rubber boa sightings along hiking trails.

4: Milk River

A plains hognose snake playing dead

Plains hognose snakes will roll onto their backs and play dead when disturbed as a defense against predators.

©Matt Jeppson/Shutterstock.com

The 729-mile-long Milk River is a tributary of the Missouri River and the second-longest river in Montana. It originates in the Rocky Mountains of Montana, flowing north into Alberta, Canada, and then southeast to join with the Missouri River near Fort Peck, MT.

The Milk River gets its name from its distinct milky color, which is a result of the fine clay and silt sediments that erode along the river basin in Alberta. Snakes you may encounter in the Milk River include the common garter snake, bullsnake, prairie rattlesnake, racer, and hognose snake.

5: Bighorn River

Wild Bighorn Sheep in the Rocky Mountains of Colorado.

In 1805, fur trader Francois Larocque named the river for the bighorn sheep he saw roaming along its banks.

©iStock.com/Gary Gray

Named for the big horn sheep living along the riverfront, the Bighorn River is a tributary of the Yellowstone River. It flows 461 miles through Wyoming and Montana. Snakes you can find in and around the Bighorn River include the common garter snake, rubber boa, and prairie rattlesnake.

The National Park Service of Montana warns visitors to the nearby Bighorn Canyon to watch out for the dangerous prairie rattlesnake. The prairie rattlesnake is common in the area, and experts estimate there is an average of one snake per acre living in the canyon.

Summary Of The Most Snake-Infested Rivers In Montana

RankRiverSnakes Found
1Missouri RiverCommon garter snake, plains garter snake, terrestrial garter snake, bullsnake, prairie rattlesnake
2Yellowstone RiverCommon garter snake, terrestrial garter snake, bullsnake, racer snake, prairie rattlesnake, northern rubber boa
3Clark Fork RiverCommon garter snake, terrestrial garter snake, bullsnake, rubber boa, prairie rattlesnake, racer snake
4Milk RiverCommon garter snake, prairie rattlesnake, terrestrial garter snake, prairie rattlesnake
5Bighorn RiverCommon garter snake, terrestrial garter snake, bullsnake, rubber boa, prairie rattlesnake, racer snake
A table snake-infested rivers in Montana

Other Animals Found Near Rivers in Montana

Moose in shallow water

Moose are strong swimmers and can hold their breath underwater for up to a minute.

©Mark Byer/Shutterstock.com

Sparsely populated by people, Montana supports a diverse array of wildlife. Many animals living in Montana rely on the state’s rivers and other freshwater sources for survival. Some of the many fish species swimming in the rivers include troutcatfishbasswalleye, and sturgeon.

Some of the larger mammals you may find around the banks of Montana’s many rivers include mooseblack bearselk, big-horn sheep, and grizzly bears. Additionally, other animals that live near the many rivers and streams in the state include white-tail deerbeaversriver otters, and muskrats.

Muskrat eating grass on river. Cute common brown water rodent animal in wildlife.

Weighing two to four pounds, muskrats inhabit freshwater rivers across Montana.

©Anton MirMar/Shutterstock.com

Finally, many bird species make their homes near rivers in Montana. Some of these include geeseswansduckspheasantsosprey, and bald eagles.

The photo featured at the top of this post is © melissamn/Shutterstock.com

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About the Author

Jennifer Geer is a writer at A-Z Animals where her primary focus is on animals, news topics, travel, and weather. Jennifer holds a Master's Degree from the University of Tulsa, and she has been researching and writing about news topics and animals for over four years. A resident of Illinois, Jennifer enjoys hiking, gardening, and caring for her three pugs.

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