By evaluating the health of waterways across the US, researchers have identified about one-third of rivers and streams that, if conserved and restored, could sustain the nation's freshwater biodiversity in the face of habitat degradation and climate change. Mark Anderson of the Nature Conservancy, US, led the new study, published September 16, 2026, in the open access journal PLOS One.
During the past century, streams and lakes in the US have deteriorated, as more than 150,000 dams have fragmented river networks, and changes to the landscape and groundwater usage have altered how and where the water flows. Many freshwater species are now in rapid decline, exacerbated by the impacts of climate change.
To address this crisis, The Nature Conservancy worked with 66 freshwater conservationists to map out freshwater networks in the contiguous US and evaluate their resilience to degradation. Each watershed was scored based on its connectivity, condition, water availability and naturalness of flow, and checked against local surveys of freshwater biodiversity. They put together a patchwork of rivers and streams – named the Freshwater Resilient and Connected Network – that covers 35% of the lower 48 states but could preserve our freshwater biodiversity. Conserving this network will be challenging, however, as currently, only 6% of the area is both protected and resilient, and 14% needs both protection and restoration.
The analysis also showed that of the 5.2 million miles of rivers and streams in the contiguous US, 33% rated as above-average for resilience. While rivers that are above average should continue to support similar patterns of biodiversity in the future, those just above average may still require restoration. These networks are concentrated in the Pacific Coast, the Northern Rocky Mountains, Great Lake areas in Wisconsin and Minnesota, Northern Maine and coastal regions along the southeastern US and the Gulf of Mexico. Vulnerable or below-average river networks made up 15% of those miles and were concentrated in the Southwest deserts, lower New England, the shortgrass prairie east of the Rocky Mountains and the agricultural lands of the midwestern states.
The study provides a solid foundation for conservation efforts to sustain biodiversity in freshwater systems and provides a clear picture of the challenges ahead. Researchers said the analysis has already been used to identify dams for removal, prioritize land protection in key headwaters and improve conditions in river systems that need restoration. The team acknowledges the maps do not take into account human needs, but data representing human dimensions could be combined with this analysis to identify them.
The authors add: "Resilience to climate changes adds important context to our efforts to conserve freshwater biodiversity. We hope our study will help our state, federal, Tribal and other conservation partners make investments where they have the greatest chance to succeed into the future."
In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/4Ae7W6j
Citation: Anderson MG, Olivero AP, Barnett AR, Khoury ML, Martin EH (2026) A freshwater resilient and connected network to sustain biodiversity under a changing climate. PLoS One 21(9): e0351782. https://doi.org/10.1371/journal.pone.0351782
Author countries: USA.
Funding: Anonymous Donor, Volgenau Foundation, Kia America, and Enterprise Mobility Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
