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Project in Niterói transformed the edge of the Piratininga Lagoon into a park with filtering gardens, bike paths, and squares, using nature-based solutions to treat rainwater, retain sediments, and reduce impurities before the flow reaches the lagoon system.
At the edge of the Piratininga Lagoon in Niterói, the Parque Orla Piratininga Alfredo Sirkis stands out as a public leisure area, but it also functions as an environmental structure created to treat rainwater before it reaches the lagoon system.
Behind the bike paths, squares, viewpoints, and social areas, the project uses vegetation, sediment retention, and natural processes to improve water quality without resorting to chemicals in the treatment of the flow that reaches the lagoon.
According to the City Hall of Niterói, the project includes 35 thousand square meters of filtering gardens, installed to act on rainwater and water from the three main hydrographic basins that flow into the Piratininga Lagoon.
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These basins include the Cafubá, Arrozal, and Jacaré rivers, which conduct part of the urban drainage to the lagoon system, carrying materials that can compromise the environmental quality of the water body when not properly retained.
In a public area of 680 thousand square meters, the solution has become more than just technical infrastructure and has integrated into a park open to circulation, leisure, culture, and environmental education in the Oceanic Region of Niterói.
Filtering gardens in Niterói function as a natural filter
In practice, the filtering gardens operate similarly to constructed wetlands, where water passes through structures designed to slow the flow and favor natural retention and treatment processes.
During this journey, particles are retained, vegetation participates in the absorption of organic matter, and microorganisms present in the environment help break down pollutant components, according to the technical description released by the municipality.
Before reaching the filtering gardens, part of the water passes through sedimentation basins, designed to retain suspended solids and reduce the silting of the Piratininga Lagoon, an essential step to decrease the load carried by drainage.
In Brazilian cities near rivers, canals, and lagoons, the water that flows through the streets during rains often carries sediments, waste, and organic matter, increasing the pressure on aquatic environments already impacted by urbanization.
In this scenario, the intervention in Niterói stands out because it transforms an urban margin into a visible environmental facility, bringing the public closer to a function that is usually hidden in galleries, pipes, or drainage structures that are barely noticed.
Parque Orla Piratininga integrates lagoon recovery
Planned within the Programa Região Oceânica Sustentável, the PRO Sustentável, the park was created to protect and recover the Piratininga Lagoon and its surroundings, while reorganizing the city’s relationship with the lagoon margin.
The area includes the islands of Modesto, Pontal, and Tibau, as well as circulation spaces, leisure facilities, and environmental structures that are part of a broader proposal for the recovery of the lagoon system of Niterói.
Among the planned and implemented urban elements are 10.6 kilometers of bike paths connected to the cycling system of the Região Oceânica, 17 leisure areas, viewpoints, and an eco-cultural center focused on environmental education.
By incorporating these facilities, a water recovery project gains a function of permanence and coexistence, allowing residents and visitors to occupy the space while the filtering gardens continuously act on the water that reaches the lagoon.
Due to the scale of the intervention, the Niterói City Hall classifies the Parque Orla Piratininga as the largest project in Brazil based on nature-based solutions in the field of environmental sustainability.
The same source reports that the project received an investment of R$ 100 million and is part of a set of municipal actions aimed at the environmental improvement of the Piratininga Lagoon and its urban surroundings.
Nature-based solutions treat stormwater
The functioning of the filtering gardens depends on the combination of engineering, vegetation, and water management, forming a sequence of structures that control the flow, retain pollutants, and increase the time the water passes through the system.
Macrophyte plants are part of this technology because their roots help absorb organic matter, while the environment formed in the gardens favors biological processes associated with breaking down pollutant particles present in the drainage.
Although it does not replace the need for sanitation and correct connections to the sewage network, the structure acts on the water that arrives through natural and urban drainage, reducing impurities before being released into the lagoon system.
Complementary structures are also part of the solution, such as rain gardens, bioretention swales, sedimentation basins, and spillways, each with a specific function in controlling the flow and retaining materials carried by the water.
The visual difference reinforces the appeal of the project, as the treatment takes place in open structures integrated into the landscape, allowing the public to observe the environmental function of a park designed to go beyond leisure.
Instead of operating as an invisible work, the system transforms the water’s path into part of the urban experience, showing how drainage, environmental recovery, and public use can occupy the same space.
Niterói Project Gained National Visibility
Outside of Niterói, the filtering gardens of Piratininga were presented as an example during a technical visit linked to WRI Brazil, with representatives from ten Brazilian municipalities interested in low-carbon urban solutions and environmental recovery.
The experience has also become a practical case for cities studying alternatives to the traditional drainage model, especially in areas where rivers, canals, and lagoons receive a large volume of rainwater.
Recognitions in awards related to sustainability and smart cities have increased the park’s visibility, cited by the City Hall as a winner of national and international awards in categories related to sustainable urban development, ecosystem services, energy, and the environment.
Despite the technical complexity, the central point of the story remains simple: a public area by a lagoon also started functioning as a kind of giant urban filter.
The rainwater, which previously would have quickly flowed into the lagoon system carrying part of the accumulated load along the way, now passes through structures designed to retain, slow down, and treat this flow before being released into the Piratininga Lagoon.
By combining environmental recovery, urban drainage, and leisure, the Parque Orla Piratininga shows how a work visible to citizens can assume functions that go beyond the landscape and help protect water quality.
While bike paths, squares, and viewpoints attract the public, the filtering gardens address a less perceptible but crucial issue for the future of rivers, canals, and lagoons in Brazilian urban areas.
Do you think other Brazilian cities should transform riverbanks, canals, and lagoons into natural filters open to the public, combining leisure, urban drainage, and environmental recovery in the same space?
