California is home to 2 of the most endangered rivers in the nation. Which ones?
California has more than 188,000 miles of rivers and streams, with major waterways winding through Sacramento, Modesto, Fresno and other cities, according to the Public Policy Institute of California
California’s $4.1 trillion economy relies “heavily” on rivers for its water supply as well as electricity and recreational activities, the nonprofit think tank said.
However, data center development, mining and pollution are “putting river health and public well-being at risk,” according to American Rivers.
The nonprofit conservation organization recently ranked the most endangered rivers in the United States in 2026 — and two California rivers made the top 10.
See where they ranked:
What is the most endangered river in California?
In 2026, the most endangered river in California was the San Joaquin River, according to the American Rivers report.
It was the second-most endangered river in the nation, the group said.
The San Joaquin River originates in the high Sierra Nevada and travels more than 300 miles through the Central Valley before reaching the San Francisco Bay delta, merging with the Sacramento River at one point. Along the way, it’s fed by the Merced, Stanislaus and Tuolumne rivers.
The upper reaches of the San Joaquin River are diverted into the Friant Dam.
The river is the “primary water source” for more than 30 million Californians and nearly half of California’s $61 billion agricultural economy,” American Rivers said, and a “lifeline” for endangered Chinook salmon.
The San Joaquin River Restoration Program aims to to restore 150 miles of the San Joaquin River from the Friant Dam to the confluence with the Merced River, allowing fish to move freely once more.
One threat to the San Joaquin River’s health is a massive gravel mine proposed by Cemex that could alter the river’s flow, expose the water supply to pollution, and stall completion of the San Joaquin River Parkway if approved, American Rivers said.
What other rivers are endangered in the state?
Another California river landed lower on American Rivers’ list of the most endangered rivers in the nation, taking the No. 9 spot.
Known as the “Crown Jewel of the Mojave Desert,” the Amargosa River is the only free-flowing river in the Death Valley region of the Mojave, providing a rare and lush riparian area in the desert.” the National Wild and Scenic Rivers System said.
The river runs through Inyo and San Bernardino counties before crossing state lines into Nevada.
The river “flows mostly underground but surfaces in a few places,” the Amargosa Conservancy said.
However, American Rivers said, proposed claystone mining expansion near the Amargosa River’s headwaters and along the borders of Ash Meadows threaten to “pollute the river and impact the groundwater essential to the river’s flows.”
“Dewatering of open pits may put groundwater-fed springs in Ash Meadows and Death Valley National Park at risk of destabilization or drying, which would be catastrophic for the river’s fragile wildlife,” American Rivers said.
Endangered animals including the Amargosa vole and Amargoda River pupfish live in or near the river.
What are 10 most endangered rivers in the country?
According to American Rivers, these 10 rivers face the greatest threats from pollution, mining and more:
- Potomac River in Maryland and Virginia
- San Joaquin River in California
- Boundary Waters in Minnesota
- Lumber River in North Carolina and South Carolina
- Rogue River in Oregon
- Chilkat River in Arkansas
- Nissequogue River in New York
- Dan River in North Carolina and Virginia
- Amargosa River in California and Nevada
- Suwannee River in Florida
How did American Rivers identify at-risk waterways?
American Rivers said it reviews nominations for the America’s Most Endangered Rivers report from people and organizations across the country, and evaluates them based on this criteria:
- A decision in the coming year that will impact the river’s fate
- The magnitude of threat to the river and its communities
- The significance of the river to people, wildlife and nature
“Each year since 1984, local leaders have teamed up with American Rivers to use the report to save their local rivers, consistently scoring policy successes that benefit clean water and communities,” the nonprofit organization said.
This story was originally published April 22, 2026 at 1:59 PM with the headline "California is home to 2 of the most endangered rivers in the nation. Which ones?."
