: Given the city’s environmental challenges, the Water LA program and its collaboratives build pathways to partnerships between agencies, non-government organizations, and the private sector to realise work at all levels. Through a case-study of a parcel-scale water management project in the City of Los Angeles, they explore the social, environmental, and economic impacts of retrofitting residential property into spaces of water capture, conservation, and reuse. These interventions transform parcels into spaces that help heal and improve the urban environment and improve quality of life. To highlight the targeted, small-scale nature of these strategies, they refer to this approach as “urban acupuncture.”
Water LA provides a case study of 22 parcel-based retrofits (rain grading/rain gardens, infiltration trenches, permeable paving, parkway retrofits) carried out in LA’s San Fernando Valley. Detailing the program’s successes and hurdles, they aim to provide actionable information for urban stakeholders seeking to implement parcel-scale, nature-based solutions across their cities in a widespread, systematic manner.
Over the course of the Water LA programme, the project team was able to amend a number of restrictive building codes, developing a streamlined greywater system permitting process, legalising a range of permeable paving materials for driveways, and developing new city-wide standards for parkway basins. (Perisho, Randle, Winter, 2018; The River Project, s.a.).
: 6 communities in Los Angeles County
: Panorama City, Studio City, Florence-Firestone, West Whittier, La Puente, Altadena
Increased provisioning of ecosystem goods (e.g. Food, water, etc)
Yes, 1.2M gallons of water captured and treated, and 55 gallons of water used per capita per day after retrofits. (Perisho, Randle, Winter, 2018).
Increased infiltration, water retention and flood protection
Diverse native plant communities also build soil structure and stability, creating resistance to wind and water erosion. Increasing soil’s organic matter can increase its available water-holding capacity. Slowing, spreading and infiltrating water reduces peak flow, increasing opportunities to absorb water before downstream facilities overflow. Healthy soil can increase water infiltration and hold up to 20 times its weight in water, significant factors in minimizing flood impacts. (Perisho, Randle, Winter, 2018, The River Project, s.a.).
Improved air quality
Soil and plants are effective filters. A diverse structure of plants, from ground covers to shrubs and trees, can absorb compounds toxic to humans as nutrients, and can reduce localised concentration of particulate matter by as much as 60%. (The River project, 2018).
Improved water quality
Plants and soil effectively regulate water quality by reducing sediment loading, capturing pollutants and cycling nutriens. Wetlands and riparian woodlands can remove 20-60% of metals, capture 80-90% of sediment from runoff, and eliminate 70-90% of nitrogen. Hydrologic modelling data indicates that the reworked properties absorb a substantial amount of rainwater into the ground, decreasing pollution in the region’s waterways and recharging the underground aquifers. (Perisho, Randle, Winter, 2018; The River Project, s.a.).
Reduced drought risk, cooling effect, urban heat island mitigation
Native plants and healthy soil are foundational for climate resilience. Mulch, soil and deeep-rooted shrubs and perennials sequester even more carbon and greenhouse gases (GHGs) than trees. Soil also absorbs carbon. The homes retrofitted by Water LA provide 18,175 square feet of diverse native plant communities (more than 6,000 plant species) for shade, evapotranspiration and carbon sequestration benefits. A diverse structure of plants, from ground covers to shrubs and trees, absorbs CO2 and other GHGs and can reduce localized concentrations of of nitrogen dioxide (greenhouse gases) by as much as 40%. Integrating nature into dense urban areas can help reducing peak summer temperatures by as much as 9°F. (Perisho, Randle, Winter, 2018; The River Project, s.a.).
Biodiversity conservation or increased biodiversity
Yes, 18,175 square feet of native vegetation planted. Native plant landscapes do not require fertilizers or soil amendments, and most native wildlife such as birds and pollinators depend upon them. (Perisho, Randle, Winter, 2018; The River Project, s.a.).
Yes, through solutions relying predominantly on soil and vegetation to restore natural ecosystem processes. Examples include: strategically undeveloped mountains and floodplains; wetlands, rain grading/rain gardens; mulch; soil conservation and enhancement; tree and vegetation planting; and parkway basins. (The River Project, s.a.).
Increased quality and quantity of green and blue infrastructures
Residential property is the largest land use in Los Angeles. Taking the Water LA Program to scale would significantly increase the quality and quantity of green infrastructure in the region.
Yes, the Water LA Program is an active approach to tackle critical environmental challenges in the City of Los Angeles, building a resilient region by making small, distributed changes to the urban landscape through working with small, nature-based solutions—and streamlining practices and policies to support their scaled-up implementation for a sustainable future. In the context of NbS implemetation to ensure water security and climate resilience, the programme outcomes indicate that the reworked properties absorb a substantial amount of rainwater into the ground, decreasing pollution in the region’s waterways, recharging the underground aquifers, reducing water use by an average of 25% in a year and increasing green infrastructure by 18,175 square feet. (Perisho, Randle, Winter, 2018; The River Project, s.a.).
Improved aesthetic value
Once established, well-selected native plants require little maintenance, and arrangements can accommodate aesthetic benefits such as aroma, color, and seasonal interest. (Perisho, Randle, Winter, 2018).
Creation of green jobs relating to the construction and maintenance of NBS
The local municipality workforce is facing a shortage of vocationally trained workers insofar as concerns the design, implementation and maintenance of green infrastructure. The activities of the Water LA Program support the development of skills for the implementation and maintenance of nature-based infrastructure as a solution to the local labour shortage.
Increased access to green infrastructure
The program focuses on distributed, parcel-based residential NbS.
Increased communities' sense of ownership
Participants participate in the selection and design of projects, and commit to ongoing stewardship.
Increased willingness, participation, investment in NBS
Yes, through collaborative partnerships between agencies, non-governmental organizations, and the private sector at all levels—from regional capital projects to neighbourhood-scale green streets and park improvements, down to parcel levels with nature-based solutions. (Perisho, Randle, Winter, 2018).
Education, knowledge exchange and learning
Yes, through trained urban acupuncture practitioners, educational events and readily available materials. Programme participants also reported an increased interest in environmental issues. (Perisho, Randle, Winter, 2018).
Climate change is creating more extreme conditions, leading to longer dry periods and more intense storms. Most of the city’s stormwater is managed through an extensive network of concrete street gutters, storm drains, and flood control channels, with the flows being directed out to the Pacific Ocean. This network of “grey infrastructure” was established in response to early-20th-century floods, which severely damaged property adjacent to the LA River and its tributary streams. Over time, this network of grey infrastructure led to the serious reduction of natural groundwater recharge. Meanwhile, models suggest that precipitation within the region will likely become flashier, heightening flood risk. These conditions were exacerbated by the extensive urbanization that took place across the county during the second half of the 20th century, replacing water-absorbing landscape with impervious surfaces like concrete, asphalt, and turf grass. Today, LA’s water management and aging infrastructure are considered increasingly precarious, due to a number of environmental, legal, and political stressors. (Perisho, Randle, Winter, 2018).
Low air quality
In 2020, there were 157 days when the region exceeded the federal health standard for ozone pollution (the most since 1997), and had more than 30 days of excessive fine-particle particulant pollution. (Barboza, 2020).
Low water quality
There are over 5,900 miles of rivers and streams in the Los Angeles region that exceed federal water quality standards for pollutants such as metals, fecal indicator bacteria, pesticides, nutrients, and trash. (California Water Boards, 2016).
Drought and heat risk
Long, seasonal dry periods and droughts, as well as short periods of heavy rainfall, characterize LA's Mediterranean-type climate. Climate change is creating more extreme conditions, leading to longer dry periods and more intense storms. (Perisho, Randle, Winter, 2018). L.A. County as a whole has experienced reduced photosynthetic activity, plants are assimilating less carbon, and native vegetation is experiencing extreme water stress due to the ongoing drought. The reduction in greenness also reduces the benefits of vegetation on urban heat island. (Our County, 2018).
Loss of biodiversity
Los Angeles lies within one of the 35 recognized biodiversity hotspots in the world. It is unique for its high natural resources including over 150 threatened and endangered species and 37 vegetation alliances, while also having the highest human density of any U.S. city. This presents many challenges for fostering biodiversity within the human-dominated landscape. A preliminary analysis of L.A.’s urban biodiversity indicates that there are many opportunities to protect and enhance urban biodiversity in LA. The study represents the first effort by the City of L.A. to manage and enhance urban biodiversity and recognize it as a priority initiative within the City’s Sustainability Plan. (Reid-Wainscoat, 2020).
The Water LA program reduces hardscapes, facilitates onsite water management and supports habitat biodiversity (The River Project, s.a.). Patterns of urban development have had a profound impact on L.A. County ecosystems. Most flat areas in L.A. County have been built upon and development has spread to the foothills, as well as on many of the region’s important alluvial fans that serve to recharge groundwater and buffer urban development from wildlands, and even the steepest slopes. The lower watersheds have been developed even more intensely with most streams and rivers having been channelized. L.A. County has lost 98% of its historic wetlands. “Edge effects” from development, site engineering, pets, light and noise pollution, and changes to natural processes such as fire suppression, hydrology, and habitat fragmentation degrade habitat quality and ecosystem function. (Our County, 2018)
Low availability of green infrastructure
Yes, Los Angeles is the densest urban centre in the US (Laidley, 2015). For L.A. County as a whole, peak greenness has decreased since 2011 and extreme lows have occurred since 2013 (Our County, 2018). Recent preliminary analysis indicate that LA needs to focus on increasing connectivity between natural areas and improve access through a more equitable distribution of natural areas. (Reid-Wainscoat, 2020). Los Angeles has made investments in grey/green infrastructure in recent years, but still predominantly funds grey infrastructures. (The River Project, 2018)
The Los Angeles region has among the worst income inequality in the nation. Per the RAND Corporation, before the pandemic-related shutdowns, the average unemployment rate was 6.6% for lower-income families and 2.1% for higher income families. Since the pandemic hit, the unemployment rate in households earning above $100,000 was only 11%. For lower-income families, it has hovered around 28%. (Ward, 2020). The Water LA Program seeks to develop a workforce to design, implement and maintain nature-based infrastructure. These are critical skillsets lacking in local municipalities.
Negative environmental impacts on human health
Environmental changes in L.A. County are affecting human wellbeing too. Ecological imbalances, combined with climate change, are already promoting the local emergence and spread of previously unseen diseases such as West Nile Virus (Harrigan et al., 2014; Our County, 2018), while pollution and changes in allergenic pollen production can trigger asthma attacks and worsen allergic symptoms in adults and children (Declet-Barreto & Alcorn, 2015). The need to better coordinate ecosystem health and human health has never been more urgent (Our County, 2018).
Food security (SDG2) Zero Hunger
Good health and well-being (SDG3)
Clean water and sanitation (SDG6)
Industry, innovation and infrastructure (SDG9)
Reduced inequalities (SGD10)
Sustainable cities and communities (SDG11)
Climate action, resilience, mitigation and adaptation (SDG13)
Harrigan, R.J., Thomassen, H.A., Buermann, W., Smith, T.B. 2014. A continental risk assessment of West Nile virus under climate change. Global Change Biology (2014) 20, 2417–2425. https://doi.org/10.1111/gcb.12534.