Municipal policies for managing stormwater with Green Infrastructure

The concept of green infrastructure offers a model for sustainable construction and development. An example of past failures is the way that the built environment contributes to disastrous floods. The US Environmental Protection Agency applies the principles of green infrastructure to storm water management by encouraging developers and residents to take more eco-friendly options.

The challenge

Green infrastructure has been defined as “all green and blue spaces in and around our towns and cities. The term allows us to refer to – and consider the collective value of – all of these spaces at once.” [1] At its broadest, green infrastructure refers to “an interconnected network of green space that conserves natural systems and provides assorted benefits to human populations”. [2] It is seen as benefiting environmental, economic and human health and wellbeing.

Many communities in the US are concerned about the interaction of “blue spaces” – such as rivers, streams, lakes and estuaries – with infrastructure developments and urbanisation. Traditional construction of infrastructure, such as roads, and public buildings or domestic housing cover large areas of the ground with impervious surfaces. Once such developments have been built, rainwater runs offsite at levels that are much higher than occur naturally. The result can be serious flooding, a phenomenon that has been seen throughout the world, from the UK’s Lake District to the American Great Lakes.

The federal government’s Clean Water Act of 1977 was an important step in protecting blue spaces, but thirty and forty years on there has been a pressing need for green infrastructure initiatives.

The initiative

In order to implement its green infrastructure objectives in storm water management, US public administrations apply the following broad policy initiatives:

  • Strengthen storm water regulation and make it more predictable and more supportive of green infrastructure.
  • Review and revise local codes to encourage, or insist on, a green approach in new developments.
  • Conduct demonstration and pilot projects, focusing on testing and developing green partnerships.
  • Manage capital and transport projects – municipal governments can create and preserve sustainable spaces by integrating green infrastructure into major projects.
  • Run education and outreach projects to emphasise the value of storm water as a resource.
  • Charge storm water fees under appropriate legislation to secure sustainable funding.
  • Offer storm water fee discounts and other incentives  to encourage compliance – municipalities want high participation rates in discount programmes in order to see green infrastructure retrofits.

The public impact

Instead of limiting the scope of storm water efforts to the regulatory framework outlined in the Clean Water Act, the most innovative municipalities are starting to link together the site-level and municipal performance of green infrastructure systems to larger regional performance and benefits. For example:

  • Open Space Seattle 2100 is a project that was established in 2006 and that integrates urban planning with blue space planning, models future scenarios, and presents the potential benefits from green infrastructure systems in a sustainable Pacific Northwest.
  • The 10,000 Rain Gardens project in Kansas City is an education and outreach programme “to encourage the creation of rain gardens and other green strategies to improve water quality”. [3]

What did and didn't work

All cases in our Public Impact Observatory have been evaluated for performance against the elements of our Public Impact Fundamentals.


Stakeholder Engagement Strong

There are a number of stakeholders engaged in storm water management projects. The principal government agency involved is the Environment Protection Agency (EPA), e.g., through its Green Infrastructure Action Strategy and its Office of Enforcement and Compliance Assurance (OECA), which focuses on pollution problems.

Other stakeholders include state governments, local municipalities and environmental departments, and organisations involved in green infrastructure projects, such as the University of Washington in Seattle 2100. Implementing vehicles include Urban Waters, Partnership for Sustainable Communities, the Brownfields program, the Great Lakes Restoration Initiative, and the National Estuary Program. Local environment departments play an important role in developing and aligning all development ordinances, for example Chicago’s Department of Environment, which initiated a Green Urban Design process.

Political Commitment Good

Local municipalities and government agencies provided directors financial support to developers and other stakeholders responsible for implementing the storm water policies consistently with the principles of green infrastructure.

Incentive mechanisms allowed municipalities to act beyond regulatory authority to improve wet weather management on properties that might have fallen outside updated storm water requirements. They were able to provide incentives to owners of private property to encourage them to adopt green infrastructure practices on their property, for example “Portland, Oregon’s Ecoroof Floor Area Ratio Bonus increases a building’s allowable area in exchange for adding an ‘eco-roof’”. [4]


Clear Objectives Good

The storm water programme objectives stated at the outset have been consistently maintained by the municipalities, and address the relevant issues, such as improving storm water management and reducing the costs of applying green infrastructure principles.

Evidence Strong

All the municipalities conducted demonstration and pilot projects and evaluated the results to frame the policy, e.g., Seattle Public Utilities considered that the success of its Natural Drainage Systems programme was down to the careful design of its several contributory pilot. Some municipalities conducted surveys to evaluate their strategy e.g., The Hudson River Estuary Program, while others looked at comparable management approaches to reframe their strategy.

Other examples abound of municipalities gathering evidence before undertaking full-scale projects:

  • Lenexa, Kansas compared three alternative storm water management approaches and found that onsite detention with green infrastructure cost about 25 percent less than the old approach of retrofitting.
  • “Olympia, Washington provides an example of a pilot phase that went poorly and resulted in a revised programme. The City set very strict development standards on the healthiest stream in the jurisdiction, Green Cove Basin, but ... developers found loopholes in the regulation that resulted in poor neighbourhood design and dissatisfaction on the part of homeowners. As a result, Olympia revised its requirements and turned more attention towards street design and public rights-of-way to improve runoff conditions in this salmon-bearing watershed.” [5]
  • “The Hudson River Estuary Program recently conducted a survey on barriers to green infrastructure implementation in the Hudson Valley. We received 127 completed responses from a wide range of green infrastructure practitioners. Respondents cited cost, lack of knowledge, and resistance from local, municipal officials as the top barriers to implementation of more green infrastructure.” [6]

Feasibility Strong

The pilot projects described above were able to assess the feasibility constraints as well as accumulate evidence.

The EPA estimated in its 2004 Clean Watersheds Needs Survey that nationwide capital investments for controlling storm water and waste water pollution over a 20-year period would be US$202.5 billion, including US$9 billion for storm water management. With less federal investment, local governments and citizens need to identify and select the most cost-effective solutions to meet regulatory requirements.

Several municipalities evaluate the costs of their green initiatives to assess financial feasibility, for example the City of Seattle “established the Sustainable Infrastructure Initiative to evaluate how it spends its more than $650 million annually on capital projects.  This interdepartmental initiative considered sustainable alternatives, such as green infrastructure, to typical retrofits, repairs and new projects.”


Management Strong

The municipalities in charge of green infrastructure for storm water management had there own structures in place to manage the initiative in their locality:

  • Chicago’s Department of Environment developed a framework to align all its development ordinances, for example, Green Urban Design.
  • Philadelphia established a Developer Services Committee to streamline its development review process. It resulted in a simplified process for permit review, inspection and approval.

Measurement Good

Each municipality has designed its own monitoring or review process to evaluate the impact of the programme, using parameters like the EPA’s Water Quality Scorecard. It was developed to help local governments identify opportunities to revise and create codes, ordinances and incentives for improved water quality protection.

Alignment Good

The EPA, and its subsidiaries, such as the OECA and regional EPA offices, cooperate with municipal authorities to promote the Green Infrastructure Action Strategy and apply the policy to specific instances, like storm water management. The EPA recognises the need for such collaboration and alignment to avoid inconsistent policies, permits, enforcement orders and control plans.