Improvements to water quality

In the bay of Fort-de-France, mangroves cover nearly 1,300 hectares, representing about 70% of the total mangrove area in Martinique. This plant formation, characteristic of tropical marine environments, is essential for the ecological balance of the bay. Mangroves act as filters, purifying marine and river waters, protecting the coastline against erosion, and providing habitat for various marine flora and fauna.
However, this fragile ecosystem is threatened by wave-induced erosion, urbanization, the spread of invasive species, and pollution. In response to these challenges, the French Coastal Protection Agency (Conservatoire de l'espace littoral et des rivages lacustres, CELRL) and its partners have launched an initiative to restore several mangrove areas as part of the “Contrat de la Grande Baie de Martinique" which is a collaborative initiative aimed at the sustainable management and restoration of the coastal and marine environment of the Greater Bay of Martinique. This contract typically involves partnerships between various stakeholders, including government agencies, local municipalities, environmental organizations, and community groups. The project identified several sites totaling 3.81 hectares in the Greater Bay area that require reclamation.
The project aims to restore mangrove populations by creating favorable conditions through actions such as clearing invasive species and trash, followed by replanting with white, black, or red mangrove seedlings, depending on the environmental characteristics of each site. Additionally, the initiative seeks to engage the public and youth through volunteering days and awareness campaigns (Refs 1-9).

The City of Mobile has developed and implemented a Storm Water Management Program (SWMP) as required by the regulations of the Environmental Protection Agency (Ref 1). Flooding is a significant issue in Mobile, occurring frequently throughout the town (Ref 3). The SWMP aims to protect water quality and prevent harmful pollutants in stormwater runoff from entering the Municipal Separate Storm Sewer System (MS4) area (Ref 1). Stormwater runoff refers to rainfall that does not seep into the ground but instead flows over yards, streets, parking lots, and buildings, eventually entering the storm sewer system, which directs it into creeks, rivers, bays, and the Gulf of Mexico (Ref 1). Stormwater can collect pollutants such as trash, debris, sediment, heavy metals, oils, and hazardous household materials. Additionally, development increases impervious surfaces, leading to more stormwater runoff (Ref 2).

Established in 1996, the United Nations Office at Nairobi (UNON) is the UN's official headquarters in Africa, located just 9.7 km from the heart of Nairobi. In line with the UN's global sustainability goals, the office took significant steps to reduce its environmental footprint as it expanded. According to the United Nations Environment Programme (UNEP), buildings contribute to a third of global energy use and are major sources of greenhouse gas emissions. To address these issues, new buildings were designed to prioritize energy and water efficiency, with a focus on sustainability.
Completed in 2011, the new headquarters reflect the UN's broader commitment to reducing greenhouse gas emissions. The design includes 6,000 m² of solar panels, rainwater harvesting systems, energy-efficient lighting, and natural ventilation, making the complex energy-neutral and water-efficient. It generates as much solar energy as it consumes, supporting over 1,200 staff members. Additionally, the project carefully preserved indigenous trees and created micro-ecosystems within the interior gardens, further aligning with the UN’s environmental mission.
By embedding these green features, the UNON complex serves as a model for sustainable development in urban settings, echoing the UN’s efforts to combat climate change and promote ecological resilience globally. (Ref. 1, 2, 3, 4)

Rapid urbanization and a population density of 6,247 people per km² have placed significant stress on Nairobi's natural resources (Ref 1). The 40-km long Nairobi River Basin, originating from the Ondiri Swamp, serves as a vital water source for the city (Ref 1, 2). However, it has suffered severe pollution from untreated sewage, solid waste, industrial contaminants, plastics, and agricultural runoff (Ref 1, 3). This degradation has had a serious impact on the ecosystem, local residents, and biodiversity (Ref 3).

To address these issues, the Nairobi River Basin Programme (NRBP), sponsored by UNEP, was launched in 1999 (Ref 4). Since then, government and non-state actors have worked together on solid waste management, riparian restoration, and wastewater control (Ref 1). The program was implemented in two phases: Phase I (2003–2006) and Phase II (2006–2009), involving stakeholders from the government, private sector, and civil society (Ref 1, 4, 5). Despite these efforts, a study from 2017 found significant tree removal along the river, and between 1988 and 2014, encroachment into the 30-meter riparian buffer zone dramatically increased, particularly between 2010 and 2014, further degrading the river’s health (Ref 1).

The John Michuki Memorial Park was transformed from a vast dumpsite in 2008 and established in honor of John Michuki, the Environment Minister during the Kibaki administration, in 2012. Michuki garnered admiration and accolades for his enthusiasm and determination to clean and preserve the environment (Ref 1, 2). Situated along the Nairobi River, the park serves as a historically rich recreational facility (Ref 3).
However, several issues arose after the park was transferred to the county administration in 2013 (Ref 2). A section of the Nairobi River flowing through the park experienced severe environmental degradation due to illegal discharges and poor waste management, negatively impacting the riparian ecosystem and biodiversity (Ref 4). Additionally, the park became a refuge for drug users, street children, and thieves, with stray dogs posing safety threats in the area (Ref 1, 2).
As the first project within the Cleaning Up Kenya Campaign, the restoration of Michuki Memorial Park was launched in 2020 by the government (Ref 5). The park is now managed by the Kenya Forest Service (KFS) following a directive from the national government (ibid.). With funds from the treasury, a perimeter fence was erected, a 2.4 km walkway was constructed, and 4,200 seedlings and 6,357 indigenous trees were planted, along with the establishment of a nursery (Ref 1, 6). A total of 20,000 tons of solid waste were removed (Ref 6). Additionally, a community forest association was formed to ensure community engagement (Ref 2).

The PARC Rain Garden project in Plymouth, Michigan, is an innovative initiative led by the Plymouth Arts and Recreation Complex (PARC) and Friends of the Rouge, aimed at addressing stormwater management and enhancing local environmental quality. Supported by a $400,000 grant from Michigan’s Department of Environment, Great Lakes, and Energy (EGLE) through its Nonpoint Source Program, this project will involve the construction of over 31,500 square feet of rain gardens located on the property of Plymouth Arts and Recreation Complex (PARC). These gardens are designed to filter up to 240,000 gallons of stormwater per rainfall event, preventing runoff from entering local waterways like the Tonquish Creek. The rain gardens will also mitigate flooding, reduce pollution, and create a more stable water flow in the Rouge River watershed, which is heavily impacted by urban development.
In addition to their environmental benefits, the rain gardens will provide aesthetic and ecological value to the PARC campus. The plantings, featuring native Michigan species, will create habitats for pollinators such as bees, butterflies, and birds, complementing the existing beehives on the PARC rooftop. The project aims to showcase the feasibility of integrating green infrastructure into routine construction, encouraging its adoption in other urban areas and residential spaces.
Ultimately, the PARC Rain Garden project will not only improve stormwater management but also serve as a model for sustainable urban development, enhancing the landscape while fostering environmental stewardship in the Plymouth community.
(Ref.1,2)

Chandler Park, a historic park in Detroit constructed in the 1800s, underwent multiple expansions from 1922 to 1950 to include amenities such as a pool (later converted into a water park), a golf course, and public green spaces. In 2013, an expert panel recommended constructing a 2.5-million-gallon marshland within the park to provide a unique recreational and educational feature and incorporate green infrastructure principles for improved stormwater management. Completed in December 2019, the Chandler Park marshland was a collaborative project between The Greening of Detroit and the Chandler Park Conservancy, designed to enhance Green Stormwater Infrastructure (GSI) across 200 acres.
The marshland manages 2.5 million gallons of stormwater, substantially reducing the load on Detroit’s combined sewer system and minimizing basement flooding during heavy rains. Engineered with rain gardens, bioswales, and a pump system circulating up to 4 feet of water, the marshland fosters a balanced ecosystem with higher oxygen levels, benefiting local flora and fauna.
With 4,500 native plants, the marshland supports diverse wildlife, including migrating birds, turtles, frogs, pollinators like bees and butterflies, and natural mosquito predators. This project not only contributes to flood mitigation but also improves water quality by capturing stormwater and allowing pollutants to settle.
Additionally, the marshland provides a foundation for future environmental education, with plans to add an outdoor classroom and public learning spaces. The use of native plants ensures low maintenance and sustainability, requiring minimal water and fertilizers. By creating new habitats and recreational areas, the Chandler Park Marshland promotes biodiversity, environmental education, and community engagement, while alleviating urban runoff’s impact on Detroit’s sewer system.
(Ref.1-3)

The Panke is a watercourse that rises outside Berlin and reaches the urban area of the city, flows through the districts of Pankow and Mitte and flows into the Berlin-Spandau Ship Canal in Wedding. The length of the Panke is around 29 kilometres. Almost the entire length of the Panke in Berlin (around 17.6 km) is to be renaturalised - on the section from the state border in the north of Berlin to its confluence with the Berlin-Spandauer-Schifffahrtskanal (BSSK). The Panke is currently a small watercourse that has been heavily remodelled by humans. In large parts of the watercourse, the banks have been straightened like a canal and reinforced with sheet piling, among other things. Existing riverbed drops and weirs prevent fish from travelling unhindered through the watercourse. Studies on water body (structural) quality, typification and other biological quality characteristics have shown that the Panke has poor status values in the majority of Berlin's sections, e.g. in terms of the fish population. The negative assessment results are primarily attributed to the lack of habitat and structural diversity, the lack of passability of the watercourse and, in some cases, high nutrient loads. (Ref. 1)

The restoration of the river was initiated by the State Berlin, following the European Water Framework Directive. The central aim is to implement flood plains and recreate the pre-straightened water course, to ensure space for flooding, habitats for more diverse flora and fauna, increase water flow for better water quality and create a site for recreation in a densely built city. (Ref. 1; Ref. 2) The project started back in 2003 and is expected to be finished in the 2030s (Ref. 2; Ref. 7).

The Rimac River Special Landscape Project, developed by the Municipal Programme for the Recovery of the Historic Centre of Lima (PROLIMA), is a municipal proposal that arose as a response to the significant degradation of the Rimac River as it passes through the historic centre of the Peruvian capital. The river has lost its character as a green corridor and potential public recreational space for citizens (1, 3). The main problems affecting the river are related to the erosion and risk of flooding of the river space, the ecological degradation of its channels and banks, the disconnection and low quality of adjacent public spaces and the urban fragmentation caused by car-oriented mobility (2). To recover its essence as an ecological green corridor, it was proposed to give back to the Historical Centre its riverside identity and to recover the water, environmental and scenic landscape. This project aims to restore the Rímac to its role as a geographical heritage and backbone of the city of Lima, creating a system of accessible and sustainable public spaces that will help to recover this water, urban and historical landscape, as well as providing a better quality of life for the residents and users of the Historical Centre (1).
The project consists of 4 stages of intervention: Puente del Ejército - Puente Santa Rosa / Puente Santa Rosa - Puente Balta / Puente Balta - Límite
of the CHL to the east (5). Among the interventions that make up the Special River Landscape Project are: the renaturation of the 4 km of the Rimac River as it passes through the city, the construction of 14 parks, 7 squares, 1 tree planting project, 24 street renovation projects, 7 bridges/pedestrian walkways, 10 building rehabilitations and 2 new public facilities (4). It is planned to start implementing the project by the end of 2024 (4).

A new landscape plan for the Santry River, developed since 2019, envisions it as “the backbone of a green infrastructure project,” designed to support nature, pedestrians, and cyclists. The project will create a continuous route from the Dublin Bay Biosphere at St Anne’s Park to the wider hinterlands of Dublin at Sillogue.
The plan proposes transforming the Santry River into an “integrated green-blue landscape for ecology and recreation,” incorporating a variety of sports, cultural, and leisure activities. Through an agreement with Fingal County Council and the National Transport Authority, Dublin City Council has commissioned studies to address the existing flood risks along the river.
The council’s goals for the Santry River include river restoration, flood mitigation, greenway development, and environmental protection, extending from the river’s origin in Harristown within Fingal County to its outlet at James Larkin Road. The project framework will span four years, with annual reviews and budget assessments.
The project team has engaged the public in early autumn of 2022 to gather input on these plans, as the Santry River project aims to create a vibrant River Park that integrates natural and recreational elements. Running through North Dublin, this new green-blue infrastructure will serve both ecological and community needs, offering opportunities for sports, culture, and relaxation. Ultimately, it will form a natural corridor linking the Dublin Bay Biosphere at St Anne’s Park with Sillogue, promoting biodiversity while enhancing accessibility for pedestrians and cyclists (2).