While green infrastructure is a concept that includes multiple strategies and has a variety of impacts, perhaps the most important component of green infrastructure is water management. Water management includes reduction in peak discharges in rivers, reductions in pollutant loading to surface waters, groundwater recharge, and reduced use of water. Historically, urban stormwater runoff has been considered a liability. Management strategies focused on removing runoff through a highly connected system of pavement and pipes. Constructed ponds and constructed and natural wetlands were used to filter the water and delay and lessen the peak discharge. Studies eventually showed that this pipe and pond system was only marginally effective and did not adequately prevent flooding and pollutant loading of receiving waters.
Over the past two decades there has been increasing emphasis on retaining stormwater runoff near the point where precipitation falls. This has been accomplished through a variety of infiltration practices. These practices, when properly designed, constructed, and maintained have proven to be effective in reducing pollutant loads and stormwater runoff volumes. However, initial designs often did not consider additional benefits that could be realized with these practices, such as carbon sequestration, habitat development, and aesthetics.
This page provides a detailed discussion of the relationship between stormwater management and green infrastructure, including a discussion of stromwater practices, integrated stormwater management, and design for multiple benefits.
Human activities can negatively impact hydrologic and chemical cycles, pollute air and water, degrade soil, and reduce biodiversity. Failure to maintain basic ecosystem functions places humans at risk because of our dependence on these functions. As human populations and resource consumption increase, it becomes even more important to preserve basic ecosystem functions. Sustainability is the principle and practice of creating and maintaining the conditions under which humans and nature can exist in productive harmony to support present and future generations. Green infrastructure is one tool or approach to creating sustainable urban environments.
The natural environment provides basic services required for humans and all life to survive. These ecosystem services can be divided into four basic categories or types.
Numerous studies attempt to place a dollar value on ecosystem services, though the value of these services is infinite in the sense that human survival depends on them. Costanza et al. (2014) place an annual value of 125 to 145 trillion dollars on ecosystem services, which is more than double the global GDP. The authors also estimate an annual loss of 4.3 to 20.2 trillion dollars, underscoring the negative impact humans are having on basic ecosystem functions necessary for our well-being.
A central tenet of sustainability is that we must preserve ecosystem services necessary for humans to survive and prosper. In 1987, a World Commission on Environment and Development report (UN, 1987) defined sustainable development as "development that meets the needs of the present without compromising the ability of future generations to meet their own needs".
A challenge is incorporating basic sustainability concepts into social and economic systems. These systems historically have not placed proper value on ecosystem services, resulting in the degradation of these services. For example, stormwater in urban areas was traditionally viewed as something that negatively impacted humans, primarily through flooding. Traditional stormwater systems were designed to discharge stormwater to the nearest receiving water as quickly as possibly. The result was a dramatic change in urban hydrology, increased flooding downstream, reduced water quality, and loss of habitat. Sustainability stresses using stormwater as a resource. Using stormwater as a resource restores some natural resource function and provides economic and social benefit. Sustainable practices achieve a balance between environmental, social, and economic factors.
Green infrastructure is an approach to managing urban wet weather impacts that mimics, restores, or maintains natural hydrology. Green infrastructure includes a wide array of practices, including infiltrating, evapotranspiring, or harvesting and using stormwater. On a regional scale, green infrastructure is the preservation or restoration of natural landscape features, such as forests, floodplains and wetlands. On the local scale, green infrastructure consists of site and neighborhood-specific practices, such as bioretention, trees, green roofs, permeable pavements and cisterns. Regional and local practices are coupled with policies such as infill and redevelopment that reduce overall imperviousness in a watershed.
Green infrastructure is an important component of sustainable urban communities. Green infrastructure helps maintain ecosystem services in the following ways.
The following section provides detailed information on each of these.
An increasing focus on Green Infrastructure has brought an awareness that stormwater management can provide numerous benefits beyond improving water quality and urban hydrology. Trees, for example, provide a multitude of benefits beyond stormwater management, as discussed in this article. In particular, vegetated stormwater best management practices (BMPs), including tree-based systems and other bioretention systems, offer opportunities to achieve multiple benefits, ranging from aesthetics (see, for example, this presentation by Dr. Steven Rodie from the University of Nebraska - Omaha) to ecosystem friendly designs.
It is clear that pollinators, both vertebrates and invertebrates, are in decline (see , , , , ). Vegetated stormwater BMPs can be designed to be pollinator-friendly. The following sections provide numerous links to information that can be used in designing and implementing pollinator-friendly stormwater BMPs.
Although much of the information on these pages is general, many of the practices can be incorporated into vegetated stormwater BMPs.
Carbon sequestration is the capture and long-term storage of carbon from atmospheric carbon dioxide. Carbon sequestration is often discussed in the context of climate mitigation, but there are numerous benefits to increased carbon (organic matter) content in soils, including improved soil structure, infiltration through soil, nutrient retention and cycling, and pollutant attenuation.
The primary mechanism of carbon sequestration is through enhanced vegetative growth.
pollination, carbon storage, hydrology, pollutant management
diverse habitats, diverse gene pool
Sustainable communities are places that balance their economic assets, natural resources, and social priorities so that residents' diverse needs can be met now and in the future.
Communities want to protect their water quality while also getting the greatest possible benefit out of every investment they make. Many are conserving, restoring, or enhancing natural areas while incorporating green infrastructure practices, such as trees, rain gardens, green roofs and other practices. These green infrastructure practices mimic natural systems into developed areas to manage rainwater where it falls. Green infrastructure practices are an integral component of sustainable communities because they can help communities protect the environment and human health while providing other social and economic benefits, allowing communities to achieve more for their money. Using green infrastructure practices strategies to reduce stormwater runoff can strengthen efforts to preserve open space and natural areas and encourage development in existing communities. These practices help make neighborhood streets and greenways pleasant and safe for walking and biking and reinforce a sense of place. Integrating green infrastructure and sustainable communities encourages collaboration in development decision and promotes green building practices.
Sustainable communities that fully integrate green infrastructure approaches use community design to help simultaneously achieve environmental, economic, and social goals. These goals include improving water quality, revitalizing neighborhoods, reducing flood risk, and providing recreational areas that encourage physical activity. Community planners can enhance these and other benefits by selecting the types and locations of green infrastructure practices that best support their goals.
To learn more about sustainable communities and green infrastructure, including how to develop a Sustainable Communities and Green Infrastructure Plan, read the EPA's report on Enhancing Sustainable Communities with Green Infrastructure.
A living street is new type of street that is narrower and has less pavement than existing streets. Reducing the width of existing streets reduces construction costs and allows room for the installation of trees and rainwater gardens to treat stormwater. Where there is a need, bike trails and sidewalks are installed to provide for safe pedestrian and bike movement. Living streets are designed for cars, people and the environment. Rainwater gardens and street trees remove pollutants from stormwater before the water enters area lakes, helping to improve lake quality. Narrower streets and street trees also slow traffic, creating a safe environment for everyone. In 2012, the City of Maplewood partnered with the Ramsey Washington Metro Watershed District to install a living streets demonstration project. For more detailed information about the project, go to the Ramsey Washington Metro Watershed District web site.
Green streets achieve multiple benefits, such as improved water quality and more livable communities, through the integration of stormwater treatment techniques which use natural processes and landscaping.
One principle of green infrastructure involves reducing and treating stormwater close to its source. Green streets provide a source control for a main contributor of stormwater runoff and pollutant load. In addition, green infrastructure practices complement street facility upgrades, street aesthetic improvements, and urban tree canopy efforts that also make use of the right-of-way and allow it to achieve multiple goals and benefits.
Green streets can incorporate a wide variety of design elements including street trees, permeable pavements, bioretention and swales. Successful application of green techniques will encourage soil and vegetation contact and infiltration and retention of stormwater. Bioretention is a versatile green street strategy. Bioretention practices can be tree boxes taking runoff from the street, as well as planter boxes or curb extensions. Permeable Pavement systems have an aggregate base which provides structural support, runoff storage and pollutant removal through filtering and adsorption. Tree trenches and tree boxes reduce stormwater runoff, help to reduce the urban heat island effect, improves air quality and urban aesthetics.
Costanza, Robert, Rudolf de Groot, Paul Sutton, Sander van der Ploeg, Sharolyn J. Anderson, Ida Kubiszewski, Stephen Farber, and R. Kerry Turner. 2014. Changes in the global value of ecosystem services. Global Environmental Change. 26:152-158.
'Definition of GI:' this is what’s in the manual now:
green infrastructure -means a wide array of practices at multiple scales that manage wet weather and that maintains or restores natural hydrology by infiltrating, evapotranspiring, or harvesting and using stormwater. On a regional scale, green infrastructure is the preservation or restoration of natural landscape features, such as forests, floodplains and wetlands, coupled with policies such as infill and redevelopment that reduce overall imperviousness in a watershed. On the local scale, green infrastructure consists of site and and neighborhood-specific practices, such as bioretention, trees, green roofs, permeable pavements and cisterns
Notice all the green call-out boxes for green infrastructure.
'GI BMP’s: '
'GI and Climate Change/Adaptation/Resiliency'
The MPCA’s Stormwater Program has been addressing the issues related to climate change adaptation since 2005 with the first issuance of the Minnesota Stormwater Manual. It advanced the concept of treating water on site, using low impact design, and volume control best management practices (BMPs). Since then, stormwater permits have advanced these BMPs, and MPCA has worked to set goals and quantify credits for using these BMPs through the Minimal Impact Design Standards (MIDS) Project. Consistent with MIDS are BMPs that can increase infiltration and reduce runoff (including green infrastructure like rain gardens, urban forestry/trees, pervious pavement, swales, etc.) Local units of government have traditionally worked to get water off the landscape as quickly as possible. In the last couple of decades, the MPCA has started addressing pollutant and rate control. We are now beginning to address volume control. Volume control, and working to mimic natural hydrology, helps to result in less dramatic runoff events, which reduces stream erosion and scouring. Impervious surfaces are increasing faster than population growth. This increase in impervious surface coupled with larger storm events will have a significant impact on receiving waters. Stormwater capture and reuse is an opportunity to reduce runoff and reap benefits from heavier rainfalls while reducing demands on the potable water supply.
NOAA Atlas 14 updates are being utilized to more accurately reflect precipitation intensities and durations. NOAA Atlas 14 incorporates 50 additional years of data into the estimate of precipitation 27 intensity and durations, and could account for changes that may be related to climate change. These estimates, used as an engineering standard, are vital to ensure proper design of culverts, storm sewers, and water quality devices.
In August 2013, the reissued Municipal Separate Storm Sewer System (MS4) General Permit became effective, which regulates stormwater discharge from counties, cities, townships and other publicly owned entities in urbanized areas. The goal of the MS4 program is to prevent or reduce the discharge of pollutants to stormwater, and ultimately, surface waters. This permit’s provisions will help to address problems of erosion and water pollution associated with heavy precipitation events.
Portfolio of green infrastructure in Minnesota (by region)
Green Infrastructure in schools
'GI and health benefits:'
'GI and sustainable communities:' EPA: Enhancing Communities with Green Infrastructure: https://www.epa.gov/smartgrowth/enhancing-sustainable-communities-green-infrastructure
'Green Streets and Living Streets. City of North St. Paul: http://www.ci.north-saint-paul.mn.us/vertical/sites/%7B5F63881B-2F96-4032-818C-7F4AD3529485%7D/uploads/%7BAF05CD7B-64EC-4FA8-A5BF-55F91637C22A%7D.PDF and City of Maplewood: http://maplewoodmn.gov/1014/Living-Streets
'For municipalities: '
Integrating GI : EPA: GI Opportunities that Arise During Municipal Operations: https://www.epa.gov/sites/production/files/2015-09/documents/green_infrastructure_roadshow.pdf Meet permit requirements with GI:
GI and brownfield development:
'Link to other reports:' EQB
|Stabilization schedule must be no less than:|
|14 days for all exposed soils|
|7 days if a discharge point is within one mile of a special or impaired water|
|24 hours for areas within 200 ft of a public water during fish spawning times|
|24 hours for areas of ditches and swales within 200 ft of the property edge or surface water discharge point and 14 days for remainder|