5 most polluted rivers in the US

The 5 Most Polluted Rivers in the US

Rachel Lark - January 17, 2023

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When you think of heading to the river, you probably envision images of lazy days on the shore, sipping a brewski while hauling in the evening’s catch. Perhaps you picture your favorite first-date picnic spot. 

However, many of these once-pristine locations face severe threats from environmental destruction. Their waters become unsafe for swimmers and downright deadly for native wildlife. Here are the five most polluted rivers in the U.S. 

1. The Ohio River 

Manufacturers design steel-hulled boats to last for 20 years or more. The water in the Ohio River is so acidic from the pollution that they rust out in three. 

Although legal advances like The Clean Water Act resulted in significant improvements to previous pollution levels, there’s still far to go. The Environmental Protection Agency named the Ohio River one of the nation’s most polluted again in 2015.

Industrial contaminants make up the most significant part of the mess, including the “forever” chemical perfluorooctanoic acid. Although parts of the Ohio River are safe for recreation, even drinking water, you can’t say the same for the tributaries. 

Many of these tributaries add agricultural runoff and sewage to the water system. Human and animal waste contaminate waterways with bacteria. Fertilizers cause eutrophication, creating liquid so rich in nutrients it inspires toxic algae blooms. These colonies then choke out the underwater plants and animals by blocking the sunlight they need to survive. 

These tributaries run through some of America’s poorest areas. Many such residents go on to develop health problems. Unable to afford the care they need, they suffer and die prematurely, often through no fault of their actions — merely from using the water where they live.

2. New River 

The trouble at the U.S. southern border involves more than immigration. Indeed, manmade pollution poses a severe threat to those seeking amnesty or a better life. New River or Rio Nuevo in Spanish, separates California from Baja, but attempting a crossing at this location could cost you your health. 


A mere splash of the liquid in your mouth can make you violently ill. Even touching the water can cause you to break out in painful sores, hence the danger to those looking to slip past the guards. 

You would think owning a waterfront property would skyrocket your home’s value. However, people near New River endure odor so bad that it causes headaches and allergy-like nasal and eye symptoms. Some go on to develop severe health problems, including cancer. 

The primary problem is industrial waste, although sewage also plays a role. The Mexican and U.S. governments have spent $91 billion over the past two decades to address the problem, but it remained. The border location makes it challenging to maintain consistency in oversight. 

3. The Mississippi River 

People have long used the Mississippi River as the line of demarcation between east and west. Its central location makes it a critical water source for the agricultural needs of the U.S. midwest. 

However, its convenience to area farmlands also creates trouble. Agricultural runoff contributes to the extensive eutrophication that endangers many larger animal and plant species. 

Fortunately, increasing regulations and economic incentives give big farms the push to change their practices. Individual residents can also take action. Don’t apply fertilizer when rain is in the forecast to prevent runoff. Avoid pesticides and mulch grass clippings instead of washing them into drains — organic waste adds nutrients to waterways that encourage algae blooms. 

4. The Cuyahoga River 

Can a river catch fire? Residents of Cleveland, Ohio, discovered that the answer is yes. The Cuyahoga River burst into flames on 13 separate occasions by 1969. Why? The sewage content was so high, it ignited. 

Fifty years later, the historic waterway still struggles to recover. However, the image of the blaze inspired former President Richard Nixon to form the Environmental Protection Agency in 1970. 

Despite cleanup measures, the waterway remains endangered. Fish populations have never rebounded, and some that survived have tumors and other deformities. Pollution still leads to beach closures and algae blooms. 

5. The Delaware River

The Delaware River would turn the hulls of ships brown, so pervasive were contaminants in the water. During WWII, water-borne illnesses abounded and the native fish population decreased. 

Fortunately, the Delaware River is also an environmental success story. It now supports native fish populations, and canoes and kayaks dot its shores. While parts of the river remain unfishable or swimmable, it’s significantly improved, thanks to environmentalists’ efforts. 

The Most Polluted Rivers in the US 

Living near a natural waterway should be a dream come true. However, it’s a nightmare for some people, thanks to pollution. 

Contaminated rivers don’t remain contained. It’s everyone’s responsibility to live more sustainably, decreasing overall river pollution and preserving nature’s resources for all to enjoy. 


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About the author

Rachel Lark

Rachel serves as the Assistant Editor of Environment.co. A true foodie and activist at heart, she loves covering topics ranging from veganism to off grid living.