The millions of miles of rivers and streams that flow across our planet might appear to be a near-infinite source of freshwater. But rivers, streams, lakes, and ponds together make up only 0.007% of the freshwater on Earth (the rest is in ice caps, glaciers, and groundwater), and many are severely threatened by pollution, dams, and diversions—human-created ills that reduce how well those bodies of water can help sustain people and other species.
In many parts of the world, rivers and streams are so polluted that they can no longer support aquatic life and are poisoning residents. In Africa, Australia, Russia, and South America, diversions of major waterways for agriculture and other uses have altered seasonal flooding of basins to an extent that is affecting centuries-old wildlife migrations and causing changes in the climate. A study published in the journal Nature in 2019 determined that only 37% of rivers more than 1,000 kilometers (621 miles) long remain free flowing over their entire length and only 23% flow uninterrupted to the ocean. In the United States, dams have cut off ancient spawning routes, driving alarming declines in some salmon populations and affecting entire ecosystems that rely on those species.
Fortunately, it’s not too late to reverse these trends, if policymakers around the world recognize the immense value of healthy and free-flowing rivers and act quickly and ambitiously to protect them. To celebrate World Rivers Day on Sept. 25, here are eight benefits of safeguarding rivers.
The condition of rivers directly affects the quality of the drinking water they provide. Water from clean, healthy rivers requires less filtration than water from polluted rivers.
Since the dawn of civilization, rivers have played central roles in culture and history—as trading routes, ceremonial sites, and the heart of human settlements. To Indigenous Australians, rivers are living ancestral beings. Tribes in western North America hold annual salmon spawning celebrations. The ancient Egyptians held their Wepet-Renpet (New Year’s) festival on the Nile. And along the Chaitén coastline in Chilean Patagonia, Indigenous people carry on ancestral shellfishing, fishing, seaweed gathering, and other cultural practices.
Riparian areas—the land that borders rivers—are some of the most diverse, dynamic, and complex habitats on Earth, according to research published by the Ecological Society of America.
Rivers account for only a fraction of the 0.007% of Earth’s freshwater mentioned above, but they support a disproportionately large amount of biodiversity. For example, freshwater habitats are home to almost 10% of all animal species, including one-third of all invertebrates. According to the International Union for Conservation of Nature, “[o]ver 140,000 described species—including 55% of all fishes—rely on freshwater habitats for their survival.”
Around the world, free-flowing rivers draw legions of boaters, anglers, and other outdoor enthusiasts. Chile’s Futaleufú River, like other internationally renowned whitewater runs, has become an epicenter of recreational and tourist activities. Futaleufú Riverkeeper, a local organization, launched the Chicas al Agua (Girls on the Water) program to teach high school girls how to kayak and educate them about local environmental issues, producing not only kayakers but also “Guardians of the Futaleufú.”
In addition, 2020 data from the U.S. Bureau of Economic Analysis indicates that outdoor recreation activities in the United States generated $688 billion in economic output and supported 4.3 million jobs nationwide. Of that, boating, fishing, and other river-related activities accounted for more than $30 billion in U.S. annual gross output. That spending directly benefits businesses of all sizes and boosts the economies in rural and urban communities nationwide.
River channels, canyons, and flood plains form over eons to accommodate changes in water levels. Altering river flows, for example through the construction of dams or culverts, disrupts those natural controls, disconnects rivers from critical flood plains, and often puts communities at higher risk of catastrophic flood damage. Further, many dams are so old they’ve become hazards to nearby communities. Failures in 2017 at Northern California’s Oroville Dam and Puerto Rico’s 90-year-old Guajataca Dam exacerbated storm flooding and forced the evacuation of tens of thousands of people.
Rivers serve as one of nature’s primary transportation systems, carrying nutrients, minerals, and fine sediments to the ocean—often from alpine environments hundreds of miles away—and facilitating the transfer of other nutrients back upstream, through migrating species such as salmon.
Free-flowing waterways within unaltered, connected river systems shuttle sediment to flood plains, providing critical habitats and food for wildlife and plants. Sediment that collects in river deltas often created natural buffers to help protect coastal areas from sea-level rise. The mouths of free-flowing rivers harbor an extremely rich biodiversity of birds, marine mammals, fish, and other marine species.
These nutrient transfers can drive entire industries, such as the prawn and barramundi fisheries off Australia’s northern coasts.
Flooding large areas with dams can cause microorganisms to break down organic matter—the trees and grasses that had lined a river, for example. When this process occurs without oxygen it often releases methane, a known greenhouse gas, into the atmosphere. One study published in 2016 in the journal Bioscience found that annual global greenhouse gas emissions from reservoirs are on par with what the entire nation of Canada emits—about 1.3% of human-caused emissions. Removing dams and restoring and protecting free-flowing rivers can reduce that percentage.
Rivers feed people—fish, freshwater snails, mussels, crayfish, and more. Across the world many Indigenous and local communities rely on healthy rivers as their “supermarkets.” Studies have shown that more than half the protein consumed in many Indigenous communities in northern Australian river basins comes directly from fishing in rivers and hunting on the flood plains that they nourish. In the U.S. Pacific Northwest, Tribes have depended on salmon as a primary food source for thousands of years.
By working to protect and restore free-flowing rivers around the world, policymakers can show their commitment to a healthy and sustainable future, for their constituents and all life on Earth.
Steve Ganey is a vice president and Lauren Spurrier is a senior director with The Pew Charitable Trusts.