How Green Infrastructure Helps Communities Manage Stormwater

Green infrastructure is not placed randomly. MMSD uses a combination of data, long-term experience, and community conditions to decide where it can have the greatest impact.

Over time, this approach has grown and improved as we've learned more about how storms affect different parts of the region.

Major flooding events in 2008, 2009, and 2010 showed how flooding is connected to pavement, limited tree canopy, urban heat, and pressure on the sewer system. These lessons helped shape MMSD's Regional Green Infrastructure Plan in 2013, which guides investments in areas with the greatest need. Many of these areas are also communities that have experienced long-term underinvestment.

In 2023, MMSD began developing a new planning tool to strengthen how green infrastructure is prioritized across the region. The tool was launched at the end of 2025 and continues to evolve as we learn more. We are currently working to include lessons from the major storms in August 2025 and April 2026.

Today, MMSD brings together a wide range of information to identify priority areas, including:

• Flooding patterns and past storm events
• Areas with a high percentage of impervious surfaces
• Sewer system performance and drainage conditions
• Soil type and land characteristics
• Tree canopy and urban heat impacts
• Social and economic conditions, including income, employment, and educational attainment
• Household and community characteristics, such as age, disability status, language access, and single-parent households
• Housing and transportation factors, including housing density, crowding, vehicle access, and housing type
• Access to green space, along with environmental and public health considerations, such as water and air quality

By combining this information, MMSD can identify where green infrastructure will provide the greatest benefits-not only for managing stormwater, but also for supporting healthier, safer, and more resilient communities.