Time has not been kind to our rivers. For centuries, humans have diminished, degraded and simplified rivers around the world, creating unhealthy waterways that have lost ecological value.
The good news is that our collective understanding of how to restore rivers is improving, with a greater focus on using natural systems to meet society’s needs while also protecting the environment. With nature-based management, we have an opportunity to rebuild rivers with the space and freedom they need to thrive. In turn, these healthier rivers lead to healthier communities and a healthier planet.
I spoke with Peter Skidmore, senior program officer with the foundation’s Colorado River initiative, about how restoring river health through natural processes can help us in the battle against climate change. He is the co-author of a recent article in the journal Anthropocene exploring the issue.
Can you describe some of the ways that rivers have been degraded over the past several hundred years?
As a society, we have relegated rivers and streams to constrained channels. These simplified and stabilized channels have lost a lot of their freedom, complexity and biodiversity. Starting in the 19th century, the extermination of beavers fundamentally changed the character of streams as dams were removed and riparian wetlands disappeared. With development in their valley bottoms, rivers have also lost the space to run free, flood, erode and deposit soil. The construction of dams and diversions have further constricted river flows.
What are we learning about emerging opportunities to restore the health of rivers so they can provide critical ecosystem services?
There has been a lot of hard work done to restore river health over the past few decades, but we’ve fallen short in addressing the challenge at a scale to have lasting impact. Over this time, we learned a lot about the potential of “natural infrastructure” to better manage rivers and restore their health through dynamic, natural processes. That can mean removing constraints wherever possible – setting levees back, concentrating infrastructure at a few pinch points, reconnecting rivers to their floodplains and renewing native vegetation.
Is there an example of how natural infrastructure can restore river health and improve climate resiliency?
One way is by promoting the return of beavers and beaver-related wetlands that reintroduce much-needed complexity into river systems. Messy rivers and streams – with features like braided and irregular channels, wetlands, eroding banks and gravel bars – are more diverse, dynamic and healthy. A success story is Bridge Creek, in Oregon, where the installation of beaver-inspired natural dams led to the expansion of beaver activity. These structures create a virtuous cycle of restoration that slows down water flow, revives mountain meadows and recreate stream meanders and wetlands that are ultimately maintained forever by beavers. They help maintain and retain groundwater, provide natural firebreaks and refuge for wildlife, and can alleviate the sedimentation impacts of post-fire flooding. Since 2005, Bridge Creek has had a dramatic increase in aquatic habitat and native fish populations. In addition to those fish and wildlife benefits, scientists are also finding that this kind of low-cost, low-tech restoration helps with carbon sequestration, nutrient capture and moderation of stream flow and temperature – critical ecosystems services in the face of drought and climate change.
What potential does this kind of restoration have to increase climate resiliency if done on large scale?
River ecosystems have a tremendous capacity for passive restoration if given the freedom space for dynamic interactions between the channel and the floodplain. They can literally heal themselves, often more quickly and effectively than we can. Just like humans need exercise to stay healthy, rivers also need that exercise. They need the space to move around. That’s important because, right now, ongoing development is exacerbating the impacts of a warming climate and straining the capacity of aging, expensive gray infrastructure to provide water security and protection from floods and drought. Natural infrastructure holds the potential to be a cost-effective and self-sustaining way to improve environmental health. It can be a critical component in a mix of solutions to the social and ecological challenges posed by climate change.
How is the foundation supporting natural infrastructure in the Colorado River basin?
The foundation’s five-year Environment program strategy increases our efforts to improve river and watershed health by working to improve public policy so it promotes nature-based solutions, and leveraging funding to implement them on a larger scale. We’re working with partners to test and increase the use of nature-based solutions that improve water security for farms and cities and also provide environmental benefits. We’re investing in beaver-related restoration that re-establishes wetlands and begins to restore degraded stream systems. And we’ve initiated an effort to identify and map changes in vegetated wetlands and beaver ponds throughout the basin as a way to measure progress and assess the potential of this work to provide system-wide benefit for the Colorado River.