What’s in the Clearwater River and Is It Safe to Swim In? 

Written by Cammi Morgan
Published: July 25, 2023
Share on:


Planning a trip to the Clearwater River? If you’re looking to hang out in or along this river, it’s important to learn about some of the local ecosystem. By learning about the ecology of the places we visit we can be better prepared for out trip as well as better appreciate the natural world around us.

Read on to learn about what’s in the Clearwater River and if it’s safe to swim in.

Overview of the Clearwater River

Located in north-central Idaho, the Clearwater River flows 74.8 miles westward from the Bitterroot Mountains along the Idaho-Montana border to the joining of the Snake River at Lewiston, Idaho.

Three main tributaries feed the main Clearwater River- these are the North Fork, Middle Fork, and South Fork Clearwater Rivers. The Middle Fork, although short, is a particularly high-volume tributary. It’s formed at the confluence of the Lochsa and Selway rivers. The Middle Fork and South Fork rivers meet to join at the easternmost end of the main Clearwater River. From the north, the North Fork drains into the Dworshak Reservoir. After this point, it heads into the northernmost, central portion of the Clearwater River.

Climate and Geography

This river spans a highly diverse topography, ranging in elevation from about 9,000 feet to 725 feet at its lowest. Along much of its path, conifer-covered and grassy hills rise in a rolling to sharp manner from the banks.

The climate along and surrounding the river is temperate with four distinct seasons. In the winter, snow and ice spread along the river’s edges and in some areas, patches of ice can form across the waterway.

During the summer, this river averages about 53 degrees Fahrenheit. Sections of this river move quite rapidly, offering plenty of whitewater activities.

Clearwater River; Lewis and Clark 1805 expedition route, Idaho

The Clearwater River is flanked along much of its path by grassy hills and patches of conifer forests.

©Joseph Sohm/Shutterstock.com

What’s in the Clearwater River: Pollution Threats

In the mid-2010s, one of the largest pollution threats to the Clearwater River was from the proposal to allow megaload trucks carrying oil-related equipment access to travel scenic Highway 12. Much of this highway winds along the Clearwater River. These trucks and their industrial cargo can weigh over 300 tons and, according to environmental and indigenous activist groups, presented multiple pollution threats to the Clearwater River. After years of litigation and direct action protests, a court settlement in 2017 banned megaloads from any future use of Highway 12.

Today, human-caused climate change and agricultural and industrial activities contribute to increased erosion that washes fine and coarse sediment into the Clearwater River. Increased levels of sediments can negatively impact some vulnerable fish populations including salmon. Finally, suction dredge mining for gold and other valuable minerals can cause pollution to this river, affecting aquatic populations and water quality.

What Animals Live Around and in the Clearwater River?

The Clearwater River provides an aquatic home, freshwater source, and hunting ground for a range of animals. These animals are all part of an interconnected ecosystem. Below, we’ll cover some of the amazing animals that call the Clearwater River region home.

Black Bear

Among the forested regions that border the Clearwater River, black bears (Ursus americanus) live and thrive. The Clearwater provides a drinking source and hunting opportunities for these beautiful animals. As non-specialist omnivores with few natural predators, American black bears have adapted to living in a range of wilderness and human-occupied environments. This species averages 50-80 inches long from nose to tail, 2-3 feet tall at the shoulders, and 175-400 pounds.

While these large and powerful critters can certainly maim or kill a human, black bears are overwhelmingly non-confrontational and certainly don’t hunt people. Black bear attacks are extremely rare and fatalities are even rarer. Still, it’s the best and most respectful course to keep your distance if you spot a black bear in or along the Clearwater River. Instead, enjoy watching these lovely animals from afar. By chance, if you happen upon one at close range by surprise, calmly back away and speak in calm tones. If the bear approaches, waving your arms, shouting, and throwing items toward them is often enough to deter these typically shy animals.

If you spot a black bear along the Clearwater River, you may observe them drinking, cooling off in the water, or hunting prized fish species like Chinook salmon and cutthroat trout.

A single wild black bear cub searches for food along a hillside overturning rocks among young evergreen trees. The young bear is only a couple of months old. There are flies on its fur and face.

In the spring and early summer months, it’s possible to spot black bears meandering along the banks of the Clearwater River or wading in the water to hunt fish.

©Dolores M. Harvey/Shutterstock.com

What’s in the Clearwater River: Chinook Salmon

The populations of Chinook salmon (Oncorhynchus tshawytscha) that inhabit the Clearwater River are federally listed as threatened. This means the Clearwater River populations of Chinook salmon, also called king salmon, are likely to become endangered in the foreseeable future, as they are in other areas of their range. Climate change, damming, habitat degradation, overfishing, and habitat loss due to development are severely threatening populations of this incredibly important species.

In the spring and summer, Chinook salmon spawn in the streams that branch off the Clearwater River. Hatchlings live in these streams for about a year. After, they migrate through the Clearwater River on their long journey to the Pacific Ocean. On average, Chinook salmon reach about 3 feet long and weigh around 30 lbs. However, some massive specimens exist that can weigh over 100 pounds and grow up to 5 feet long.

Close-Up of a Chinook Salmon During Spawning

Chinook salmon migrate through the Clearwater River annually on their way to the Pacific Ocean. They also use tributaries of the river to spawn.

©Kevin Cass/Shutterstock.com

Northern Pacific Rattlesnake

There are three venomous species of snake native to Idaho. The species with a range that includes parts of the Clearwater River is the Northern Pacific rattlesnake (Crotalus oreganus).

This beautiful snake typically reaches around 36 inches long. They feature a large triangular head and a distinctive, dark brown post-ocular eye stripe. The base body color can range quite widely on this species, depending on its environment. The body coloration usually presents as olive-gray, olive-brown, copper-brown, or light brown-gray. Along their back, they display large blotches that are the most distinctive when the snake is young. As they age, this distinctive pattern tends to fade. Towards the tail, the blotches shift to banding which ends at their prominent, segmented, and hollow rattle.

Safety Around Snakes

Hikers exploring the grasslands and forests around and banks of the Clearwater River are encouraged to avoid stepping underneath tight rocky overhangs, into tall grass, or on wood piles in this area, especially around dawn and dusk during the warm months.

Contrary to myths and exaggerated accounts, rattlesnakes don’t set out to chase or attack people. Instead, snake bites typically happen when someone accidentally steps on or is way too close to the snake. Less commonly, people even ignore the warning signs of a rattlesnake. Signs like coiling with a raised head and rattling should serve as a warning to back off. This species, like other rattlesnakes, most often choose to freeze and camouflage themselves, or flee, when presented with a threat. This is a safer option for them than risking injury in a conflict. The best way to avoid a snake bite is to be mindful of your environment and be respectful of their space.

rattlesnakes in california

The range of the Northern Pacific rattlesnake extends to the Clearwater River region.

©Ryan M. Bolton/Shutterstock.com

What’s in the Clearwater River: Is It Safe to Swim In?

Fast, strong currents in sections of the Clearwater River is likely the biggest threat to swimmer safety. If you do choose to swim in the Clearwater, make sure to choose a location without prominent white water rapids or particularly strong currents. You can likely find spots, especially in slower flow seasons like August, where the waters are much gentler.

The forest is reflected in the South Fork of the Clearwater River in Idaho, USA

If you want to swim in the Clearwater River, your best bet is to find a gentle, slow-moving part of this stunning waterway.


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

Share on:
About the Author

Cammi Morgan is a writer at A-Z Animals where her primary focus is on mycology, marine animals, forest and river ecology, and dogs. Cammi has been volunteering in animal rescue for over 10 years, and has been studying mycology and field-researching mushrooms for the past 3 years. A resident of Southeast Appalachia, Cammi loves her off-grid life where she shares 20 acres with her landmates, foster dogs, and all the plants, fungi, and critters of the forest.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.