New Map Shows Which US Rivers Need the Most Protection

A new map is helping scientists figure out which American rivers are in danger and need the most help. Researchers spent four years studying more than 5.2 million miles of rivers and streams across the lower 48 states. They found that only six percent of these waterways are in good shape, while 14 percent are struggling and need attention right away. The study was published in September and was led by a group called The Nature Conservancy.

The scientists looked at how well each river could hold up against the effects of climate change. They called this ability 'resilience,' which means how well something can recover from damage or stress. About one-third of the rivers studied were above average in resilience. However, even those rivers may still need some restoration work to stay healthy.

The rivers with the best chances of survival are found in several parts of the country. These include areas along the Pacific Coast, the Northern Rocky Mountains, the Great Lakes region in Wisconsin and Minnesota, Northern Maine, and coastal areas along the Southeast and Gulf Coast. These rivers still have clean water, connected habitats, and enough flow for wildlife to survive. Animals can move through them more freely, which helps species adapt to changing conditions.

On the other hand, about 15 percent of rivers were rated as vulnerable, meaning they had below-average resilience. These weaker rivers are mostly found in the desert Southwest, lower New England, the shortgrass prairies east of the Rocky Mountains, and the farming regions of the Midwest. Years of human activity — such as building dams, using large amounts of groundwater, and changing the surrounding land — have put pressure on these rivers. This has caused many water-dwelling species to decline rapidly over the past century.

Mary Khoury, a freshwater ecologist at The Nature Conservancy, explained why this map is so important. She told Science News, 'We can now point at a map for the first time and say, these are the rivers most capable of sustaining diversity of aquatic life, and this is what each one needs.' Khoury also said that a resilient river system gives species options and environments in which to adapt. The map can help decision-makers know exactly where to focus their conservation efforts.

Thanks to the research, some positive steps have already been taken. Certain dams have been identified for removal, which would allow rivers to flow more naturally again. Land near the sources of important rivers has been marked for protection. These actions show that the map is already making a real difference in how people protect America's waterways.

Climate change is making things harder for rivers across the country. Rising temperatures cause flooding, droughts, wildfires, and changes to groundwater, all of which hurt water quality. Warmer water can also lead to toxic algal blooms — dangerous overgrowths of algae that can harm fish and other river life and even spread disease. The non-profit National Environmental Education Foundation has noted many of these growing threats.

Two of the country's largest reservoirs, Lake Mead and Lake Powell, hit record low levels this past summer due to extreme heat and drought. Both are connected to the Colorado River, which has been shrinking for years. The Nature Conservancy warns that three-quarters of all rivers could lose their biodiversity because of climate change if nothing is done. Scientists hope this new map will inspire people and governments to act before it is too late.