The statistics are staggering: freshwater species populations have declined by 85% since 1970, more than any other ecosystem on Earth. Yet despite decades of conservation efforts, we've struggled to accurately measure whether our river protection strategies are actually working. A landmark 2026 study from Conservation Science Partners and American Rivers is changing that—and the findings should concern everyone who cares about water.

The Measurement Problem

For years, conservationists have relied on a simple approach: count how many river miles flow through protected lands like national parks and wilderness areas. If rivers pass through protected territory, they must be protected, right?

Not exactly.

The Protected Rivers Assessment of the United States represents the most comprehensive evaluation of river protection ever conducted in the country. Researchers evaluated more than 7 million kilometers of rivers and identified nearly 70 different protection mechanisms—from federal designations and state policies to local ordinances and private conservation easements.

Only 12% of U.S. Rivers Are Adequately Protected

The assessment introduces a new Protected River Index (PRI) that measures protection across five key ecological attributes essential for healthy rivers:

• Free-flowing conditions — unimpeded by dams
• Longitudinal connectivity — ability for species to move upstream/downstream
• Water quality — protection from pollution sources
• Riparian habitat — intact streamside vegetation and buffers
• Biodiversity — support for native species populations

Under this more rigorous framework, only about one-tenth of rivers in the contiguous United States—roughly 383,741 miles—are protected at a level considered viable by the scientific community. That's out of 4.4 million total river miles.

The Disconnect Between Land and Water

One of the study's most significant findings is the mismatch between terrestrial protected areas and actual river protection. Traditional land-based conservation measures often fail to address the unique characteristics of freshwater ecosystems.

Rivers don't respect boundaries. They flow across jurisdictions, connect distant landscapes, and depend on conditions far upstream. A river segment flowing through a national park might still be affected by agricultural runoff miles away or blocked by a dam downstream.

National parks alone protect 130,000 miles of rivers—about 3% of the nation's total. Of all protected rivers in the country, roughly one-tenth fl