Five Ways Climate Change is Transforming Our Home Rivers—and Why We Have So Much Left to Fight For

Rivers connect all of us. From mountains to the sea, stitching together communities, delivering safe drinking water, irrigating farms and providing all of us an unparalleled place to play—and fish. But they’re under growing stress in a changing climate. From rising water temperatures to intensified storms, these changes ripple through the delicate balance of riverine environments, affecting everything from nutrient levels to fish populations. Understanding these impacts is crucial for safeguarding the health of our rivers and the communities that depend on them and it’s why our Community Scientists are capturing vital data across the world. That data is helping us understand the shifts, shine a light when critical concerns arise—and ultimately give people the opportunity to be a part of protecting the rivers in their own backyard.

Here are five ways climate change is transforming our home rivers: increasing water temperatures, altering nutrient cycles, driving sedimentation shifts, exacerbating flooding through storm intensification and shifting hatches and fishing seasons. As you’ll see, every one of them is inextricably linked. Let’s get into it…

Water Temperature

Just like air temperature, climate change is driving up river water temperatures through a combination of those rising global air temperatures and altered weather patterns. As greenhouse gas emissions trap more heat in the atmosphere, the resulting warmer air can directly raise the temperature of river water. Simultaneously, reduced snowpack and earlier snowmelt—common in many regions—diminish the cooling effect of cold water inflows during warmer months. And compounding all of that, lower water levels caused by prolonged droughts and higher evaporation rates further concentrate heat in rivers, amplifying temperature increases. These warmer waters can have profound ecological consequences, threatening coldwater species like trout and salmon, disrupting aquatic food webs and reducing oxygen levels critical for river ecosystems.

Nutrient Changes

Nutrient dynamics in rivers are undergoing significant shifts due to climate change, impacting ecosystems and water quality. Key nutrients like dissolved organic carbon, nitrogen (in forms such as nitrate and ammonium), phosphate and silica play essential roles in aquatic ecosystems, supporting food webs and regulating chemical processes. However, climate-driven changes in precipitation, temperature and human activities are altering nutrient availability and cycling. For instance, increased runoff and erosion can elevate levels of silica and phosphate, fueling harmful algal blooms, while shifts in nitrogen levels can disrupt aquatic food webs and accelerate eutrophication. Understanding these nutrient changes is vital for managing freshwater health and mitigating broader ecological impacts. Our Community Scientists do important work, sampling for nutrients, which are key elements of every river's story.

Sedimentation

Climate change is significantly altering sedimentation patterns in rivers, with profound implications for ecosystems and infrastructure. Increased intensity and frequency of storms lead to higher erosion rates, washing greater volumes of soil, sand and debris into waterways. At the same time, melting glaciers and thawing permafrost in colder regions release additional sediment into river systems. In contrast, prolonged droughts and damming rivers reduce and change water flow, limiting sediment transport and causing it to accumulate in certain areas. These shifts can disrupt habitats for aquatic species, alter river channels and increase sedimentation in reservoirs, reducing their capacity and effectiveness. Managing these changes is crucial to maintaining healthy river ecosystems and ensuring the sustainability of human water resources.

Storm Intensification and Flooding

Climate change is heightening flood risks in rivers as intensifying storms deliver heavier and more frequent rainfall. Warmer atmospheric temperatures increase evaporation, loading storm systems with more moisture and resulting in torrential downpours that overwhelm riverbanks. These deluges often lead to flash flooding, particularly in areas with urbanization or altered landscapes that reduce natural water absorption. Hurricane Helene in the Southeast US this fall is a devastating example of how a changing climate is threatening communities. And in coastal rivers, rising sea levels further compound the issue by intensifying storm surges, pushing floodwaters further inland. The increased runoff from these events not only heightens flood risks but also carries pollutants and sediment into rivers, harming ecosystems and water quality. As Hurricane Helene reminded us in Western North Carolina, these combined pressures demand urgent adaptation and flood management strategies to protect communities and ecosystems.

Shifting Hatches and Fishing Seasons

And just like everything you’ve read so far, the changing climate is disrupting the natural rhythms of aquatic ecosystems by altering the timing of insect hatches and creating unfavorable conditions for fish. Warmer water temperatures are speeding up the life cycles of aquatic insects, causing hatches to occur earlier in the year and potentially out of sync with the feeding schedules of fish that rely on them. Meanwhile, higher temperatures can make fish lethargic, reducing their ability to forage or evade predators and in some cases, temperatures can increase so much they can be lethal to coldwater species—affecting fishing seasons and the entire ecosystem. Shifts in runoff patterns, such as earlier snowmelt or more intense storms, further exacerbate these challenges by altering water levels and temperatures, creating unpredictable and often unsuitable conditions for aquatic life.

These disruptions threaten the delicate balance of river ecosystems and the species that depend on them, something anglers know all too well. In fact, the American Fly Fishing Trade Association sounded the alarm earlier this year with Lucas Bisset, AFFTA’s executive director, saying, “We’re literally in a fight for our fishing, and if we, as anglers, can’t communicate the challenges facing our fishing from climate change, then our fishing is in real trouble.”

Thanks to our growing team of Community Scientists—and you—we’re doing just that. When we fish, when we stand strong in our home waters, we can’t help but fall in love with them. And when we take the time to get to know our rivers and the species that call them home in a deeper way, by understanding when they’re sick, when they’re telling us something, it creates an unshakeable bond and taps into a deep human instinct to protect our home. That love, that story and that home, it’s worth fighting for.

Help us build the next generation of Community Scientists.