What is the Most Endangered River in the U.S.

As the western United States faces historic drought, communities across the region are grappling with how to save the Colorado River, a key waterway that feeds 40 million people and some of the country’s largest cities but is in crisis. What is the most endangered River in the U.S. 

On 04/019/2023, American Rivers, a Washington, DC-based group that advocates for clean water & healthy rivers, voted the Colorado River the most endangered river in the U.S. According to the organization, the river has been plagued with outdated water management, over-use, & of course climate change.

The United States has over 250,000 thousand rivers but it is said that about 3.5 million US citizens get sick from these rivers such as through drinking contaminated drinking water, bathing in these waters, or eating the fish caught in these waters.

The Most Endangered River in the U.S.


The Colorado River in the Grand Canyon is the nation’s most threatened river in 2023, the nonprofit advocacy group American Rivers declared in an annual report released Tuesday 04/19/2023.

It’s the second year in a row that the group has placed the Colorado River atop its list, though last year’s designation applied to the whole river because of the region’s overuse of its water. This year, the group focused on how a dry climate and declining and limited water supply in Lake Powell are harming ecological and cultural resources in the area of the river flowing through Grand Canyon National Park.

The threat to the canyon’s river environment worsened this past when the U.S. Bureau of Reclamation held back more water than usual last year in an effort to preserve hydropower production capacity at the dam.

But that threat would worsen to unprecedented levels if the reservoir were allowed to drop below the turbine intakes, leaving just the bypass tunnels that were not designed for constant flow to keep the river moving. That would limit the government’s ability to flow enough water to protect the canyon. 

American Rivers chooses its annual list based on both the urgency of risks to a waterway and on the potential for public advocacy to influence a pivotal decision within the next 12 months.

After the Colorado River Ohio was named #2


American Rivers today named the Ohio River among America’s Most Endangered Rivers®, citing that a lack of federal designation and investment leaves this vital river and watershed vulnerable. The Ohio River is the backbone of the environment, the economy, the culture, and the history of the communities that live along the mainstream and throughout the Basin. The Ohio River watershed is the primary drinking water source for over 5 million people.

“The Ohio River is one of the most vibrant, resilient ecosystems in the country, as evidenced by its ability to support a rich assemblage of aquatic life and offers recreational opportunities for the surrounding communities, on top of serving as a major transportation corridor and drinking water source. The protection of this valuable resource against current threats is absolutely critical and essential to our region,” says Chris Lorentz, vice-chair of the Ohio River Basin Alliance.



The Ohio River Basin is one of the largest watersheds in the nation and drains from areas affected by environmental pollution from neighboring industries, including mining and resource extraction for energy production and development, chemical production, and manufacturing.

This has resulted in significant discharges of toxic chemicals, including both legacy chemicals such as mercury and dioxins and chemicals of emerging concern (especially PFAS and Gen-X chemicals) as well as acid mine drainage. These kinds of pollution are threatening human and ecosystem health.

This vulnerability is most recently exemplified by the chemical release in East Palestine, Ohio, resulting from a Norfolk Southern train derailment which created harmful air pollution and leaked hazardous butyl acrylate into the Ohio River.

The Ohio River begins at the confluence of the Allegheny and Monongahela Rivers in Pittsburgh, Pennsylvania, the river flows southwest and defines boundaries of the state of Ohio, West Virginia, Kentucky, Indiana, and Illinois before flowing into the Mississippi River in Cairo, Illinois.

American Rivers, an advocacy group based in Washington D.C. that works with communities to reduce river pollution and create policies that promote clean water and reduce flood risks, compiles an annual list of America’s most endangered rivers.

The organization named the Colorado River the most at-risk in the U.S. The federal government 2021 declared its first water shortage on the essential Western waterway, which has been the subject of interstate litigation and hundreds of millions in spending.



The Top 10 Most Contaminated Rivers in the U.S.


America’s Most Endangered Rivers® of 2023

  1. Colorado River, Grand Canyon (Arizona):

THREAT: Climate change, outdated water management
AT RISK: Ecosystem health, reliable water delivery, regional economy

  1. Ohio River (Pennsylvania, Ohio, West Virginia, Kentucky, Indiana, Illinois):

THREAT: Pollution, climate change
AT RISK: Clean water for 5 million people

  1. Pearl River (Mississippi):

THREAT: Dredging and dam construction
AT RISK: Clean drinking water, local and downstream communities, fish and wildlife habitat

  1. Snake River (Idaho, Oregon, Washington):

THREAT: Four federal dams
AT RISK: Tribal treaty rights and culture, endangered salmon runs, rural and local communities

  1. Snake River | river, United States | Britannica (Montana):

THREAT: Pulp mill pollution
AT RISK: Public health, fish, and wildlife

  1. Eel River (California):

AT RISK: Fish and wildlife, tribal culture and sustenance

  1. Lehigh River (Pennsylvania):

THREAT: Poorly planned development
AT RISK: Clean water, fish and wildlife habitat, rural and local communities, open space

  1. Chilkat and Klehini rivers (Alaska):

THREAT: Mining
AT RISK: Bald eagle, fish, and wildlife habitat, tribal culture, and sustenance

  1. Rio Gallinas (New Mexico):

THREAT: Climate change, outdated forest, and watershed management
AT RISK: Clean drinking water, farming, watershed functionality

  1. Okefenokee Swamp (Georgia, Florida):

THREAT: Mining
AT RISK: Fish and wildlife habitat, wetlands, water quality, and flow



JimGalloway Author/Editor

References: NPR- The Ohio River, which supplies drinking water to millions of people, is endangered



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