Green Infrastructure


With last year’s unusually wet winter and the next rainy season approaching, green infrastructure will be more important than ever in California. Local governments, especially in the Bay Area, are making great efforts to implement green infrastructure in their cities. Read on to learn more about green infrastructure and how to see if there’s green infrastructure in your city!


First, what is green infrastructure and why is it important? Green infrastructure is an approach to city and street planning that allows stormwater (water that washes off streets, driveways, yards, etc., picking up pollutants and flowing directly into the Bay and ocean) to be absorbed and filtered by soil and plants. Stormwater runoff is one of the largest contributors to water pollution and is mainly caused by pollutants washing off the many impervious surfaces in our urbanized areas, especially roads and parking lots. Green infrastructure provides cities with an opportunity to integrate more “green” into their communities and fight urban water pollution, a win-win scenario for everyone! Implementing green infrastructure is also an important step to help combat climate change. The Environmental Protection Agency has listed several ways green infrastructure improves resiliency for environmental change in cities:

  1. Managing floods by absorbing rainwater, which cement and concrete aren’t able to do
  2. Preparing for droughts by utilizing rain gardens and green streets to infiltrate rainwater and replenish local groundwater supplies
  3. Reducing the urban heat island effect (when an urban area is significantly warmer than surrounding areas) by increased trees and shading
  4. Lowering building energy demands
  5. Spending less energy on water management
  6. Protecting coastal areas with natural landscapes


Now that you know why green infrastructure projects are so important, here are some common types of green infrastructure that you can find in your community:

  • Rain Gardens: These are small gardens that capture and filter stormwater in shallow, plant-filled depressions.
  • Bioretention Areas: These areas are usually larger than rain gardens, but also filter stormwater and are often designed to send the clean stormwater back to the storm drain system.
  • Vegetated/Dry Swales: Swales are natural drainage paths that convey runoff and allow stormwater to filter through vegetation and soil. They often run along streets and sidewalks.
  • Green Roofs: Green roofs are vegetation installed on roof tops that catch and reduce the amount of rainfall that reaches the streets.
  • Porous Pavements: These are pavements made out of porous material (like pervious concrete, and porous asphalt) that allow rainwater to soak through the pavement.


Click here to learn more about the above forms of green infrastructure, or visit our Green Streets page to learn about green infrastructure in San Mateo County.


For more information on green infrastructure and its benefits, visit the EPA website on green infrastructure. Next time you’re on a walk in your neighborhood, take a look around. You might be surprised at what types of green infrastructure you’ll find!