Replumbing Cities from Gray to Green

March 25, 2015
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Guest Contributor

As we go about our day, most of us never stop to think about the steady flows of fresh and waste waters that happen every moment just a few feet beneath the sidewalks and streets. Kristina Hopkins, postdoctoral fellow at the National Socio-Environmental Synthesis Center (SESYNC), wishes that more people would do so—because in many cities, the systems that handle those flows are beginning to fail.

Increasingly, failing infrastructure, flash flooding, and poor water quality—problems likely exacerbated by climate change—affect the health of rivers and streams flowing through our cities. In 2013, the American Society of Civil Engineers gave the nation’s drinking water, wastewater, and stormwater systems a D grade. It’s estimated that an investment of nearly $300 billion will be required to restore our wastewater and stormwater infrastructure, while drinking water supply systems will require a $1 trillion investment over the next 20 years.

At SESYNC, Dr. Hopkins is studying how cities are addressing these problems by investing in “gray” infrastructure, which includes the installation of pipes and large storage tunnels and the upgrading of sewage treatment plants, and “green ” infrastructure, which uses soils and vegetation to slow down and filter stormwater at the source using features such as rain gardens. Working with Abby York and Nancy Grimm of Arizona State University, Hopkins is using data and reports from local agencies to determine how and why four cities—Phoenix, AZ; Philadelphia, PA; Pittsburgh, PA; and Portland, OR—are investing in green infrastructure. Hopkins seeks to answer two overarching questions:

  1. How have stormwater infrastructure systems changed over the last 20 years?
  2. What socio-political factors trigger transitions in management strategies?

At a recent seminar presented at SESYNC, Hopkins explained her hypothesis: that the ability of cities to change their management strategies to incorporate green treatment solutions depends on the amount of coordination between various civic entities and the degree to which administrative power is distributed. Cities in which a single authority oversees all elements of the water cycle and in which the planning process flows from the bottom up, Hopkins argues, are the most likely to successfully transition to new management approaches.

To better understand these dynamic relationships, Hopkins is creating a database that captures the characteristics of each city’s water service area (size, climate, infrastructure types), governance characteristics (infrastructure ownership, policy instruments, incentive programs, administrative arrangements), and performance metrics (environmental conditions, access to green infrastructure, community engagement). To test her hypothesis, Hopkins hopes to perform qualitative and quantitative analyses to identify the links between different types of governance structures and the outcomes of efforts to adapt water management approaches.

Hopkins says her work at SESYNC will advance the field of socio-environmental synthesis by identifying policies and financial investments that catalyze transitions towards resilient, stormwater management systems.

The National Socio-Environmental Synthesis Center, funded through an award to the University of Maryland from the National Science Foundation, is a research center dedicated to accelerating scientific discovery at the interface of human and ecological systems. Visit us at and follow us on Twitter @SESYNC.

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