Runoff from stormwater continues to be a major cause of water pollution in urban areas. It carries trash, bacteria, heavy metals, and other pollutants through storm sewers into local waterways. Heavy rainstorms can cause flooding that damages property and infrastructure.
Historically, communities have used gray infrastructure—systems of gutters,pipes, and tunnels—tomove stormwater away from where we live to treatment plants or straight to local water bodies. Thegray infrastructure in many areas is aging, and its existing capacity to manage largevolumes of stormwater is decreasing in areas across the country. To meet this challenge, many communities are installing green infrastructure systems to bolster theircapacityto manage stormwater. By doing so, communities are becoming more resilient and achieving environmental, social and economic benefits.
Basically, green infrastructurefilters and absorbs stormwater where it falls. In 2019, Congress enacted the Water Infrastructure Improvement Act, which defines green infrastructure as "the range of measures that use plant or soil systems, permeable pavement or other permeable surfaces or substrates, stormwater harvest and reuse, or landscaping to store, infiltrate, or evapotranspirate stormwater and reduce flows to sewer systems or to surface waters."
Green infrastructure elements can be woven into a communityat several scales. Examples at the urban scale could includearain barrel up against a house, arow of trees along a major city street, or greening an alleyway. Neighborhood scale green infrastructure could includeacres of open park space outside a city center, planting rain gardens or constructing a wetland near a residential housing complex. At the landscape or watershed scale, examples could include protecting large open natural spaces, riparian areas, wetlands or greening steep hillsides.When green infrastructure systems are installed throughout a community,city or across a regional watershed,they can provide cleaner air and water as well as significant value for the community withflood protection,diverse habitat,and beautiful green spaces.
Learn more:
- Downspout Disconnection
- Rainwater Harvesting
- Rain Gardens
- Planter Boxes
- Bioswales
- Permeable Pavements
- Green Streets and Alleys
- Green Parking
- Green Roofs
- Urban Tree Canopy
- Land Conservation
Downspout Disconnection
This simple practice reroutes rooftop drainage pipes from draining rainwater into the storm sewer to draining it into rain barrels,cisterns,or permeable areas.You can use it tostore stormwater and/or allow stormwater to infiltrate into the soil. Downspout disconnection could be especially beneficial to cities with combined sewer systems.
Examples
- Philadelphia Rain Check Program Metal Downspout Planters
- Milwaukee Downspout Disconnection
- Portland, OR, Downspout Disconnection Program
Rainwater Harvesting
Rainwater harvesting systems reduce stormwater pollution by slowing runoff and collectingrainfall for later use. The variety of systems range from the backyard rain barrel and the commercial building cistern to ground level pits, aquifers and even nets that capture dew and fog. These types of systems have been implemented world-wide.
Examples
- District of Columbia Riversmart Homes
- San Mateo County Home Rain Barrel Program
- Philadelphia Rain Check Program for Rainwater Harvesting
- Milwaukee Metropolitan Sewerage District Rain Barrels
- New York City Rain Barrel Giveaway Program
- Arizona Municipal Water Users Association
Rain Gardens
Rain gardens are small, shallow, sunken areas of plantings that collect stormwater runoff from roofs, streets, and sidewalks. Also known as bioretention cells, they are designed tomimic the natural ways water flows over and absorbsintoland to reduce stormwater pollution.
Examples
- EPA Stormwater BMP Fact Sheet: Bioretention (Rain Gardens)
- Montgomery County, MD Rain Garden Design Templates
- Hillsborough County, FL Friendly Landscaping
- 12,000 Rain Gardens in Puget Sound
- FEMA My Rain Garden Coloring Book
Planter Boxes
Planter boxes are urban rain gardens with vertical walls and either open or closed bottoms. Usually found in downtown areas, they collect and absorb runoff from streets, sidewalks, and parkinglots. Ideal forareas with limited space, planter boxes can be a useful way to beautifycity streets.
Examples
Bioswales
Bioswales, often found along curbs and in parking lots, use vegetation or mulch to slow and filter stormwater flows.
Examples
- EPA Stormwater BMP Fact Sheet: Grassed Swales
- Wisconsin Department of Natural Resources Technical Standard
Permeable Pavements
Permeable pavements infiltrate, treat,and/orstorerainwater where it falls.They can be made of pervious concrete, porous asphalt, or permeable interlocking pavers. This practice could be particularly cost effective where land values are high and flooding or icing is a problem.
Examples
- EPA Stormwater BMP Fact Sheet: Permeable Pavements
- Use of Pervious Concrete Eliminates over $260,000 in Construction Costs in Sultan, WA
- Designing Pervious: A Minnesota city eschews storm drains for pervious streets
Green Streets and Alleys
Green streets and alleys are created by integrating green infrastructure elements into their design to store and filterstormwater.Permeable pavement, bioswales, planter boxes, and trees are among the elements that can be woven into street or alley design.
Examples
- EPA Stormwater BMP Fact Sheet: Street Design and Patterns
- EPA Region 3Green Streets, Green Jobs, Green Towns (G3) Program
- Seattle Public UtilitiesGSI Projects
- Syracuse Green Street: Concord Place (PDF)(2pp, 220K, About PDF)
- Los Angeles Green Street: Elmer Ave
- The Chicago Green Alley Handbook (PDF)(24pp, 3.7MB, About PDF)
Green Parking
Many green infrastructure elements can be seamlessly integrated into parking lot designs. Permeable pavements can be installed in sections of a lot and rain gardens and bioswales can be included in medians and along the parking lot perimeter. When built into a parking lot, these elements also reduce the heat island effect and improve walkability in the area.
Examples
- EPA Stormwater BMP Fact Sheet: Green Parking
- Ipswich River Watershed Demonstration Project in Wilmington, MA
- Toronto Design Guidelines for “Greening” Surface Parking Lots (PDF)(40pp, 9.6 MB, About PDF)
Green Roofs
Green roofs are covered with growing media and vegetation that enable rainfall infiltration and evapotranspiration of stored water. They are particularly cost-effective in dense urban areas where land values are high and on large industrial or office buildings where stormwater management costs are likely to be high.
Examples
- EPA Stormwater BMP Fact Sheet: Green Roofs
- King County, WA, Green Roof Case Study Report (PDF)(31pp, 1 MB, About PDF)
- Green Roof and Wall Projects Database
Urban Tree Canopy
Trees absorb stormwater in their leaves and branches. Many cities have set tree canopy goals to restorethe benefits of trees lost when the areas were developed.Homeowners, businesses, and community groups can participate in planting and maintaining trees throughout the urban environment.
Examples
- EPA Stormwater BMP Fact Sheet: Urban Forestry
- Chicago Trees Initiative
- Philadelphia Water Department: Stormwater Tree Trench
Land Conservation
The water quality and flooding impacts of urban stormwater also can be addressed by protecting open spaces and sensitive natural areas within and adjacent to a city while providing recreational opportunities for city residents.Natural areas that should be a focus of this effort include riparian areas, wetlands, and steep hillsides.
Examples
- Green Seams: Flood Management in Milwaukee
- Alachua County, FL, Green Infrastructure Investment Program(PDF)(8pp, 233K, About PDF)
- EPA Stormwater BMP Fact Sheet: Open Space Design
- EPA Stormwater BMP Fact Sheet: Conservation Easem*nts
- EPA Stormwater BMP Fact Sheet: Protection of Natural Features
