Portland’s Stormwater Marketplace

Using Market Forces to Implement Sustainable Stormwater Management

The City of Portland received a grant from the U.S. Environmental Protection Agency in 2005 to study the feasibility of using market forces to implement sustainable stormwater management practices. In particular, the study focused on the feasibility of a credit-trading system to increase private investments in stormwater management improvements in Portland's combined sewer basins.

Stormwater Management in Portland

When rain falls in Portland, it usually runs off streets, rooftops and other impervious surfaces into the sewer system. Disposing of runoff in a storm sewer that drains to a river or stream sends dirt, metals, oil, pesticides and other pollutants right into the water. The City of Portland promotes more natural stormwater management systems – such as vegetated swales and ecoroofs - that collect stormwater and allow it to soak into the ground while soil and vegetation filter pollutants. This sustainable approach protects water quality, refreshes groundwater supplies, and relieves the burden on Portland’s sewer system.

Portland’s Combined Sewer System

Much of the city has a combined sewer system that collects stormwater runoff from streets and sewage from homes and businesses in the same pipes. These combined sewers overflow to the Willamette River when it rains. The city is installing large sewer tunnels (Big Pipes) on both sides of the Willamette River to collect that mixture of stormwater and sewage and pump it to the Columbia Boulevard Wastewater Treatment Plant.

The West Side Big Pipe is in operation. When the East Side Big Pipe is complete in 2011, the combined sewer system will overflow on average only four times each winter and once every three summers instead of nearly every time it rains. But Portland will continue to grow and develop, and the added impervious surfaces will generate more stormwater that needs to be managed. That will increase the burden on the big pipes. The stormwater marketplace will give property owners more incentives to manage stormwater onsite and will keep runoff out of the combined sewer system.

Stormwater Management Requirements

The federal Clean Water Act, Safe Drinking Water Act, and Endangered Species Act require the city to improve stormwater quality and protect watersheds, rivers, streams and drinking water resources. The Portland Watershed Management Plan uses an integrated city response to these environmental regulations. The approach allows the city to plan and implement projects like the Stormwater Marketplace that respond effectively to multiple requirements.

A Stormwater Marketplace in Portland

Preliminary findings suggest that Portland has a great untapped potential for sustainable stormwater management improvements on private property and in public rights of way; however, the costs of implementing a credit-trading system for stormwater volume controls far exceed the potential benefits. Instead, the study identifies a comprehensive set of market-based initiatives (short of credit trading) to animate private investments in sustainable stormwater management. These initiatives (1) increase public awareness and understanding of the need and desirability of on-site stormwater management; (2) facilitate the planning, design and installation of sustainable stormwater management improvements; (3) promote the creation of a local "green" economy of stormwater management designers, suppliers, manufacturers, installers and stewards; (4) use Internet-based tools to facilitate private action by linking property owners to ideas, information, expertise and vendors; and (5) use Internet sites, social networks and community institutions to accelerate public acceptance and interest in sustainable stormwater investments. These initiatives form the foundation of a self-motivating and self-sustaining marketplace for stormwater management improvements.

The City is currently conducting market research to measure Portland's propensity for private, sustainable stormwater management investments. The research will inform the development of a tool box of public policies, programs, incentives and market infrastructure; all designed to animate and establish a stormwater marketplace. The City expects to complete this final stage of the feasibility study by December 2008, and use its findings and work products to support major stormwater improvement initiatives in combined sewer basins along Willamette River.  

For more information, contact:

503-823-4038

danv@bes.ci.portland.or.us

503-823-7160

gordon.feighner@ci.portland.or.us