Weathering the Storm Where Rain Falls

Responding to the community’s flooding and water quality concerns, MMSD prioritized ratepayer involvement in developing new solutions. The agency concluded that distributed green infrastructure installed on a home or business owner’s property is highly visible and accessible, and so is more likely to gain public support. In 2002, MMSD began deploying distributed strategies including:

• Bioswales
• Permeable pavement
• Stormwater trees
• Rain gardens

and more to help capture stormwater where it falls, reduce the strain on centralized infrastructure, minimize pollution caused by overflows, and improve water quality.

Since 2002, MMSD has installed GSI projects that capture 100 million gallons of water during each storm, supplementing gray infrastructure to reduce CSOs ~2.3 overflows per year, down from 50-60 per year. By capturing stormwater and adding green space and shading, these projects provide multiple benefits to the MMSD ratepayers, including groundwater recharge, reduced carbon emissions, energy conservation, improved air quality, and water quality improvement.

MMSD’s investment in green infrastructure is also estimated to reduce the utility’s future infrastructure costs. In particular, an investment of $178 million for green infrastructure in the agency’s combined sewer service area would result in stormwater capture equivalent to $222 million investment in gray infrastructure. It creates 500 green maintenance jobs at full implementation and, on average, 160 construction jobs per year. The distributed infrastructure programs are also estimated to increase property values by $667 million throughout the MMSD service area.