What’s interesting about urban rivers?
Urban rivers play many important roles in our cities. They maintain the health of coastal and estuarine ecosystems and they are part of larger catchment ecosystems that are nested within wider, interconnected systems. Urban rivers are also essential to the quality of our drinking water, playing central roles in cultural and traditional preservation. Urban rivers offer an ecological record of what was in place before excessive human impacts as they maintained and protected the local area. They act as reservoirs for biodiversity, enhance local economies, limit and control flooding, and serve as one of nature’s primary nutrient transportation systems. However, urban development often impacts urban waterways and can be quite detrimental to the health of urban rivers and their ability to support surrounding ecosystems.
Why do urban rivers need to be restored?
Human impacts, such as pollution, dams, and diversions have accelerated the deterioration of urban river ecology, and have led to the decline of larger coastal and estuarine ecosystems. Specific issues include the alteration of the physical structure of the river (channelization, artificial banks, dredging), water quality degradation (increase run-off, sewer discharge), removal of riparian vegetation, and the presence of invasive species. Increased intensity and frequency of storms induced by climate change can cause flood risks for communities, increase polluted stormwater runoff and contaminate the river habitat, and destabilize our watersheds. While rivers embody climate threats, they are also the source of powerful solutions. A healthy urban river can be a community’s first line of defense against climate change impacts, offering cost-effective flood protection, safeguarding clean water supplies, and reducing urban heat through the evaporation and transfer of sensible heat.
One effort to restore these natural sites involves floating gardens on pallets, which can increase ecosystem resilience and benefit biodiversity of the river bank. Not only will restoration of urban rivers nourish wildlife habitat, but it has the potential to restore life and economic prosperity for nearby human communities.
What is “urban river restoration” and what are its benefits?
Urban river restoration often involves the re-establishment of natural floodplains, helping to absorb and slow the flow of excess water during heavy rainfall, reducing the risk of urban flooding. By restoring the natural capacity of rivers to manage water flow, cities become more resilient to extreme weather events, such as storms and heavy precipitation, which are expected to increase in frequency and intensity due to climate change. Further, healthy river ecosystems act as effective carbon sinks by sequestering carbon through the growth of vegetation along riverbanks and riverbeds, as well as the trapping of organic matter in sediments.
Restoring natural river systems can introduce cooling effects, moderating temperatures in urban areas. Trees and vegetation along riverbanks provide shade, and the presence of water bodies helps regulate local temperatures, mitigating the urban heat island effect exacerbated by climate change. Moreover, biodiversity increases as healthy river ecosystems provide breeding grounds for fish, support a variety of plant and animal life, and create corridors for wildlife movement. Biodiversity is essential for ecosystem resilience, ensuring that urban areas can adapt to changing environmental conditions. River restoration also increases water quality. Urbanization often leads to increased runoff of pollutants into rivers, negatively impacting water quality. Restoration projects involve the implementation of green infrastructure, such as wetlands and vegetated buffers, which act as natural filters. These measures help trap and filter pollutants, improving water quality and creating a healthier environment for aquatic life. Lastly, urban river restoration contributes to the reconnection of urban populations with nature. Revitalizing urban river spaces can help address historic environmental racism that eliminated green spaces from minority communities. Creating recreational spaces along restored urban rivers not only increases access to green spaces for residents but also fosters a sense of stewardship and community engagement in environmental conservation efforts.
How do floating gardens work?
Nick Wesley and the Urban Rivers of Chicago attempt this restoration of urban rivers through their floating gardens. Floating gardens prioritize wildlife when creating public green spaces. The Wild Mile, the floating eco-park in the Chicago River, is an accessible boardwalk with floating artificial habitats. The habitats mimic the local natural wetland ecosystem, one that could have been found in that area before the city was developed and they are pontoon-based which allows them to sit on the water and float. The flotation platforms are made of environmentally friendly materials that are built to last. These floating gardens allow the plant roots to grow through the physical framework to grab nutrients from the river
Young fish and other small river species benefit greatly from the habitat that the root system provides. Wetland plants are known to trap contaminants like heavy metals, therefore it also acts as a massive water filter. As the seasons change, these plants also aid in controlling the natural cycles of nitrogen and phosphorus. Additionally, there are submerged sections of the Wild Mile that showcase aquatic environments designed to replicate the natural riverbed. These floating gardens can rise and fall in response to variations in the water level because it is anchored to both the barrier and the riverbed. Even when the water has surged above the seawalls, the Wild Mile has withstood tremendous flooding.
About our guest
Nick Wesley is the executive director and co-founder of Urban Rivers in Chicago. He has worked with his team in order to bring the first floating park to the Chicago River, the Wild Mile, a mile-long floating eco-park, fit with floating walkways, floating gardens, and even floating forests.
Further Reading
- Urban Rivers Website
- Richardson and Soloviev, “The Urban River Syndrome: Achieving Sustainability Against a Backdrop of Accelerating Change” (Int J Environ Res Public Health, 2022).
- The River Restoration Center, “River restoration in urban areas”
- American Rivers, Rivers and Climate Change
- Park et al, “Influence of urban form on the cooling effect of a small urban river” (Landscape and Urban Planning, 2019).
- Wild Mile Chicago
- Environmental Defense Fund, Climate Change Makes River Restoration More Important than Ever
- NOAA, ”Building Community Resilience Through Habitat Restoration” (2021)
- McClain, “Restoring Rivers to Protect Communities from Climate Change” (American Rivers)
- Public Policy Institute of California, “Preparing California’s Rivers for a Changing Climate”
- Schiffman, “Ecosystems as Infrastructure: A New Way of Looking at Climate Resilience” (Yale Environment 360, 2023)
For a transcript of this episode, please visit https://climatebreak.org/restoring-urban-waterways-with-nick-wesley/
