What is Green Stormwater Infrastructure?

In natural landscapes, rain that falls on the ground mostly soaks, or infiltrates, into the soil. However, in urban areas, impervious surfaces such as roofs, pavement, and streets, prevent infiltration. This results in an increase in stormwater runoff and pollutants flowing into storm drains, local creeks, and the Bay.

Cities and towns in Santa Clara Valley are working together to create sustainable or green streets, buildings, and parking lots that mimic natural landscapes by incorporating green stormwater infrastructure features. These features allow rainwater runoff to soak into the ground and be filtered by soil. This reduces the quantity of water and pollutants flowing into storm drains and local creeks.

Green stormwater infrastructure features include the following:

• Dispersion of Stormwater Runoff into Landscaping
• Bioretention Areas or Rain Gardens
• Rainwater Harvesting and Use
• Green Roofs
• Pervious Concrete, Porous Asphalt, and Pervious Pavers
• Infiltration Trench

Local municipalities have developed Green Stormwater Infrastructure (GSI) Plans to incorporate green stormwater infrastructure features into new and existing drainage infrastructure on public properties and rights-of-way, including streets, storm drains, and parking lots. SCVURPPP has developed a guidance document (“Green Stormwater Infrastructure Handbook”) to provide guidance to municipal staff on how to incorporate green stormwater infrastructure features into public street, parking lot and park retrofit projects. Identification and maintenance of vegetation in bioretention areas is the focus of another guidance document (“Green Stormwater Infrastructure Vegetation Guide”) to assist municipal and private sector maintenance professionals.

Click on the map to the right to access the interactive data portal on Stormwater Treatment Measures (STMs) constructed to-date in the Santa Clara Valley. The data portal includes Low Impact Development (LID) and Green Stormwater Infrastructure (GSI) projects constructed on private properties and public projects constructed in the public right-of-way. For more information on how GSI features help our communities, please visit the Green Streets webpage on the Watershed Watch website.

See below for spotlight fact sheets on local and regional Green Street projects

• Martha Gardens Alley, San Jose
• Hacienda Avenue, Campbell
• Southgate Neighborhood Green Streets Project, Palo Alto

	Dispersion of Stormwater Runoff into Landscaping Landscaped areas can be designed to collect stormwater runoff from building roofs and paved areas. Stormwater infiltrates into these areas, and pollutants are filtered out or broken down by the soil and plants.
	Bioretention Areas or Rain Gardens These landscaped areas collect, treat, and infiltrate runoff using plants and a specified soil mix. Biotreatment areas can be incorporated into parking lots, curb extensions, park strips, traffic circles, and street edges and medians. Planter boxes next to buildings, tree wells, and tree trenches can also be designed as biotreatment areas.
	Rainwater Harvesting and Use Rainwater harvesting systems collect and store rainwater for later use. They slow and reduce stormwater runoff, and that stored water can be used for landscape irrigation or toilet flushing.
	Green Roofs Building roofs covered in soil and vegetation enable rain water infiltration, storage, and evapotranspiration (water loss from soil and plants to the surrounding air). In addition to stormwater benefits, Green roofs can also mitigate urban heat island effects while improving air quality and building energy efficiency.
	Pervious Concrete, Porous Asphalt, and Pervious Pavers Pervious surfaces let rain percolate through them and into the soil. They are generally used in crosswalks, sidewalks, plazas, driveways, parking spaces, street edges, and emergency vehicle access lanes. Pervious surfaces include the following: Pervious concrete or porous asphalt Grid pavers with gaps filled with gravel or turf Interlocking pavers made of pervious material Solid interlocking pavers that have gaps between
	Infiltration Trenches Infiltration trenches are excavated trenches backfilled with gravel. They capture, store and infiltrate stormwater runoff into the soil. They can be used along street edges and in alleys and parking lots.

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Green Stormwater Infrastructure Documents

Date	Title	Categories	Tags
6/30/2023	Green Stormwater Infrastructure Vegetation Guide	Other Documents, Uncategorized	Bioretention, GSI, New Development (C.3.)
2/28/2023	Identifying Green Infrastructure Potential in Municipal Capital Improvement Program Projects Guidance	Guidance Documents	GSI
9/1/2019	SCVURPPP Green Stormwater Infrastructure Handbook	Guidance Documents	GSI, New Development (C.3.)
11/29/2018	Workshop Materials – Stormwater Resource and Green Stormwater Infrastructure Planning: Opportunities for Multi-Benefit Projects in Santa Clara Valley – 11/29/18	Workshops	GSI, New Development (C.3.)
8/29/2018	GSI Handbook Workshop #2 – April 24, 2018	Workshops	GSI, New Development (C.3.)
8/29/2018	GSI Handbook Workshop #1 – April 10, 2018	Workshops	GSI, New Development (C.3.)
4/19/2017	Green Infrastructure Design and Implementation Workshop – April 19, 2017	Workshops	GSI, New Development (C.3.)