Cleaner Water for Fewer Dollars: Paving the Way

First, the bad news: Nationwide, urban development with impervious surfaces has increased 20 percent over the past two decades. The resulting increase in stormwater runoff is...
by | July 29, 2009

First, the bad news: Nationwide, urban development with impervious surfaces has increased 20 percent over the past two decades. The resulting increase in stormwater runoff is costing cities an estimated $100 billion annually to manage and contain this additional runoff. Proper management of stormwater runoff is important both to prevent flooding and to limit pollutants from entering lakes, rivers, and streams--but it can be very costly.

Now, the good news: New approaches to stormwater management are encouraging greener development, meaning local governments can avoid runoff problems without investing in costly infrastructure.

Three decades ago, the City of Bellevue, Washington, established a stormwater utility and inaugurated the first-ever stormwater utility fee. By 1980, over 20 cities and counties had formed stormwater utilities. Today, stormwater utilities and accompanying fees are commonplace. But Bellevue, Washington continues as a pioneer in stormwater management.

Bellevue's stormwater fees are pegged to the amount of impervious surface and total surface area, and also include credits for stormwater management measures and wetlands. Like all stormwater fees, these fees help Bellevue pay for stormwater infrastructure and operating costs. But they are also a catalyst for conservation--conservation that reduces the quantity of stormwater runoff and brings water quality benefits. Since permeable surfaces absorb rainwater, fees that encourage permeable rather than impervious surfaces in urban landscapes can significantly reduce runoff, help maintain water quality, and lower long-term costs of managing stormwater.

Other towns and cities are now replicating the Bellevue model. A 2007 stormwater utility survey conducted by Black & Veatch showed 9 percent of respondents using a combination of impervious and gross area to set fees. This fee structure meets the required test that city service fees must be linked to service costs. At the same time, this fee structure creates incentives for developers and landowners to reduce use of runoff-creating impervious surfaces. Some cities take a step further by also creating incentives to reduce water pollution. A third of cities surveyed indicated that they offer user-fee credits or other incentives to encourage customers to control or reduce stormwater pollution.

Three decades ago, most stormwater utilities focused on a single goal--managing stormwater to prevent flooding and associated erosion. The Bellevue, Washington fee structure reflects a broader evolution of stormwater utilities toward integrating water quality, water quantity, flood protection, habitat preservation, and even recreation goals into how stormwater is managed. The result is good for the environment and can help growing cities avoid investment in costly additional stormwater management infrastructure.

Consider what happens as pavement of roads and riverfronts, parking lots and patios, courtyards and commercial centers dominates urban landscapes. Tom Cathcart of Mississippi State University points out that a one-inch storm on a one-acre undeveloped site will experience runoff of 10 percent or less, at most generating some 2,700 gallons of runoff. In the same storm, a newly paved one-acre site, Cathcart explains, will experience runoff of 90 percent or more of the 27,000 gallons of water. "Surprise!" says Cathcart. "Conduits capable of handling 2,700 gallons per acre have trouble with 27,000 gallons per acre."

For cities, observes Cathcart, that trouble translates into more trouble--road flooding, building and property flooding, clogged drainage systems, and utility disruptions. Cathcart's figures may even understate how well permeable surfaces absorb rainwater. When one Seattle neighborhood introduced green infrastructure that included permeable rather than paved surfaces, runoff fell by 98 percent. Similar measures in Portland reduced runoff by 95 percent.

Water quality improves, too. The University of New Hampshire Stormwater Center has found that green infrastructure can reduce key pollutants in runoff by almost 100 percent. In essence, permeable surfaces filter, assimilate, entrap, and degrade pollutants. Two University of Washington researchers, Benjamin Brattebo and Derek Booth, affirmed the effectiveness of permeable pavements in reducing runoff and lowering pollution from motor oil and some heavy metals.

Under Clean Water Act regulations, cities must meet water pollution reduction goals for stormwater. Landscaping and green infrastructure that prevent pollution from entering waterways are, thus, increasingly important. In the Black & Veatch 2007 survey of stormwater utility managers, 35 percent ranked pollution monitoring as the most important measure of stormwater management success. Only flood control, cited by 42 percent of managers, was rated by more managers as the most important measure of success.

Bellevue's fee structure for stormwater management generates the revenues that enable the city to build and maintain necessary infrastructure. But, in the long term, the fee structure, by encouraging landowners to "green" their city by using more permeable surfacing, will reduce the need for expensive additional stormwater management facilities. With this basic economic benefit to cities come environmental benefits of reduced pollution and more wildlife habitat.

What is good for cities is also good for the nation. More than 25 percent of U.S. lakes have low oxygen levels as a result of pollution from chemicals and other substances. Low oxygen levels make these waters inhospitable for plant and animal life. Reducing stormwater runoff in cities can help restore health to America's streams, lakes, and rivers.

Bellevue pioneered the use of "green" stormwater fees. Today, similar fee structures in place in Seattle, Portland, Milwaukee, and several Florida cities are paving the way for less pavement in our cities--and that trend will benefit cities, citizens, and the ecosystems that depend on clean water.

Those looking for more information can visit the Florida Stormwater Association online, and view the manual "Establishing a Stormwater Utility in Florida, free download at

Lynn Scarlett, formerly Deputy Secretary and Chief Operating Officer of the Department of the Interior, is now an independent environmental consultant