Multiple benefits

Green infrastructure in cities provides innumerable benefits for both people and ecosystems. These ecosystem services can include improving water quality, mitigating flooding, cooling the urban environment, supporting biodiversity, and providing benefits for human health and wellbeing.

Considering the many benefits of urban greening helps make a strong case for building, planting, and installing green features in cities. However, some of the greatest challenges of promoting urban greening continue to be accounting for, planning for, designing for, and measuring the disparate types of benefits that green features provide.

Through Next Generation Urban Greening, we are developing a Regional Framework for the San Francisco Bay Area that can help cities and practitioners make the case for green infrastructure, and design features that will optimize the benefits that are most important to their communities.

Water quality

Contaminants that accumulate on impervious surfaces during dry weather are transported across the landscape, into the stormwater system, and ultimately into San Francisco Bay. Green infrastructure can provide water quality benefits by intercepting and soaking up rainfall, thereby reducing urban runoff. Certain types of green infrastructure can also filter contaminants in urban runoff, reducing pollutant loading to streams and the Bay.

Heat

Urban environments experience extreme heat conditions in areas with limited vegetation and canopy cover, a phenomenon known as the urban heat island effect. Trees and other vegetation provide cooling by reflecting and absorbing radiation and cooling the surrounding air through evapotranspiration (similar to how sweat cools our skin). Maximum air temperatures in the Bay Area have already increased by nearly 2^o F since 1950 and more and longer duration extreme heat events are predicted for the future. Understanding how urban greening strategies can mitigate urban heat and the priority locations for mitigation is an important benefit to consider when planning green infrastructure projects. 

Biodiversity

Increased canopy cover and overall vegetation cover constitute a substantial habitat improvement, conferring numerous ecological benefits to humans and wildlife. Increased urban green space can provide increased habitat for plants and wildlife and connect nearby habitats, improving the ability of insects, wildlife, and plants to move across the urban landscape.

Equity and human health

Urban greening, and especially planting trees, is linked to improved public health outcomes in cities, ranging from decreased co-morbidities to improved mental health and social cohesion. However, urban trees and greenery are often distributed inequitably across cities. Socioeconomically disadvantaged communities tend to have lower tree canopy cover than more affluent areas. Prioritizing urban greening in underserved and tree-deficient communities not only closes the “green gap” in cities, but can also help ameliorate other environmental justice burdens that trees and green spaces can mitigate, such as disproportionate exposure to extreme heat, air pollutants, and flooding.

SFEI has advised the planning and design of several green stormwater infrastructure projects. These projects generally prioritize improving water quality and managing runoff into the San Francisco Bay, but SFEI has contributed design recommendations that would also help generate a more diverse suite of benefits, including biodiversity support, urban heat mitigation, climate resilience, and environmental education. These projects are led by SFPUC & SFRPD in and around McLaren Park:

• Upper Yosemite Creek daylighting will daylight 1700 feet of creek to maximize contaminant reduction, urban heat island mitigation, and improve biodiversity (Partner agencies: SFPUC, SFRPD) 
• Crocker Amazon Park bioretention installation will capture parking lot runoff, remove contaminants from stormwater, and increase biodiversity (Partner agencies: SFPUC, SFRPD)
• Grey Fox Creek restoration project will support the removal of invasive vegetation, mitigate and improve trail access, and expand riparian habitat along 500 feet of the creek (Partner agency: SFRPD)
• McLaren Park Upper Reservoir Freshwater Wetland will be designed and built to reduce runoff, maximize habitat value, and replace aging infrastructure (Partner agency: SFRPD)
• Visitacion Valley Greenway Native Plant Demonstration Garden has established a new native plant garden and outdoor classroom (Partner organizations: Visitacion Valley Greenway, Community Garden program, GOAL (Growing Outdoors and Learning), SFRPD, fiscally sponsored by the San Francisco Parks Alliance)
• Redevelopment Projects in India Basin, Candlestick Point, and Schlage Lock will create accessible, resilient, biodiverse greenspace in historically disadvantaged neighborhoods along the shoreline (Partner organizations: SFPUC, SFRPD, Golden Gate Audubon, CNPS Yerba Buena Chapter)

Islais Creek Case Study

Watershed Strategy

SFEI worked with SFPUC to assess the public benefits of a series of potential green stormwater infrastructure (GSI) opportunities in the upper Islais Creek watershed. In support of SFPUC’s GSI project feasibility assessment, SFEI used models to quantify the benefits that both people and native species would derive from the proposed bioswales and street trees. Quantifying potential public benefits enabled the SFPUC to more accurately compare traditional “gray” infrastructure with GSI, and make the case for investing in green infrastructure alternatives. 

The larger Next Generation Urban Greening project will use this case study as a model to develop a Watershed Strategy that demonstrates how practitioners across the region can quantitatively measure the benefits that proposed urban greening projects can generate. The Watershed Strategy will be incorporated into the Regional Framework to demonstrate the application of urban greening strategies.

Alemany Corridor map shows where urban heat island effects are mitigated (drop in temperature) by planting trees densely in the Alemany Corridor

Regional Framework

The Next Generation Urban Greening project will culminate in a Regional Framework. The guidance resource will stitch together the many facets of the Next Generation Urban Greening project into a single framework that guides cities toward planning, designing, and implementing urban greening projects that integrate multiple benefits.

• The Framework is heavily informed by the input and feedback that we collect from practitioners across the region through our annual Next Generation Urban Greening Regional Forums. In these forums, SFEI has sought to understand the core challenges and opportunities for scaling up urban greening in the region, so that the Regional Framework–and the tools, guidance, and resources compiled within it–will directly address those needs.
• The Framework will present a systematic approach for developing a Watershed Strategy and demonstrate its application in the Islais Creek watershed. The Strategy will outline a step-by-step approach to optimize the spatial placement of green infrastructure features across a watershed in order to maximize outcomes that integrate multiple benefits.
• In response to knowledge and resource gaps that we learned about through the Regional Forums, the Framework will also compile design guidance to support the planning and development of urban greening implementation projects that achieve multiple benefits.

Regional Forum

SFEI has been hosting Regional Forums to advise the development of the Regional Framework and maximize its value and applicability to the full Bay Area region. SFEI, the Water Board, municipalities (including stormwater permittees), environmental planners, landscape architects, NGOs, and other practitioners have been meeting annually to shape the project tools. This shared learning process will enable the project to benefit from the insights of leading GSI managers around the region, while permittees gain immediate access to the innovative approaches being developed. The timing and structure will be designed to support implementation of the Municipal Regional Stormwater Permit and development of green infrastructure plans.

• Regional Forum 1
• Regional Forum 2

Fact Sheets

Illustrated fact sheets will be created to clearly and easily communicate the resources and guidance that are generated through the project. These fact sheets will be disseminated through the Regional Forum, project website, presentations, and outreach events.

Local engagement events

To gain community input and share project information, the project team will collaborate with several local organizations who host community events. The outreach strategy includes events as part of the SFPUC’s Rain Guardians series, sharing the biodiversity approach as part of the Visitacion Valley Greenway Native Plant Garden design process, and contributing to local meetings of the California Native Plant Society Yerba Buena Chapter. New watershed information will also be shared through the SFPUC’s Discover Your Watershed Mapping Project.