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Stormwater doesn't fall gently on the environment

Left to its own devices, stormwater can wreak havoc on land, water and fish.

By BRUCE WULKAN
Puget Sound Water Quality Action Team

Sometimes it feels like the rain will never stop in the Puget Sound region. And when that rain falls on hard impervious surfaces, like rooftops, parking lots and roads, it becomes stormwater.

Left to its own devices, stormwater can damage homes, businesses and streams -- affecting our economy and natural resources. The key to managing stormwater and protecting Puget Sound lies in finding more sustainable ways to accommodate growth while reducing impacts to the natural environment in which we all live.

Problem
Unmanaged stormwater can lead to flooding and damage homes and property. Photo courtesy of Puget Sound Action Team.

Environmental threats

Flooding is the most obvious problem caused by stormwater. Unmanaged or inadequately managed stormwater leads to flooding and extensive damage to homes and businesses. Building on unstable slopes that then become saturated after heavy rains can have devastating consequences, as evidenced by the loss of homes during the heavy winter rains of 1998 and '99.

Peak stormwater flows that continue for extended periods can also devastate streams used by salmon. High flows undercut stream banks, displace downed trees and gravel used as habitat and carry sediment that turns clear streams into chocolate rivers. Stormwater flows also degrade wetlands, causing exaggerated fluctuations in water levels that wash away eggs and nests of amphibians and birds.

Stormwater is also an excellent carrier of pollutants, such as toxins, nutrients, bacteria and sediment, which are produced from our daily activities. Toxins include metals and petroleum products left by vehicles on roads, driveways, and parking lots, and found in pesticides and industrial chemicals.

Toxins can impair reproduction and immune systems or prove fatal to aquatic life and threaten human health. Lawn fertilizers introduce nutrients that cause algae blooms and deplete oxygen from surface waters. Failing septic systems release bacteria that close shellfish growing areas to harvest and threaten public health. Inadequate controls on construction sites contribute sediment that clog fish gills and smother habitat needed for laying eggs. In their last report to Congress (1996) the Environmental Protection Agency reported that stormwater runoff was the second leading polluter of the nation’s estuaries.

The challenge is to ensure that stormwater is managed so that homes and businesses are protected from flooding, habitat and aquatic resources are protected from high stormwater flows, and toxins and other pollutants are not released into our waters. This is especially tough in light of our region’s tremendous growth over the last decade. Growth means more houses, roads and other impervious surfaces that generate stormwater, and less forest cover to soak up the rainfall. And since stormwater originates from rainfall it’s part of our region’s hydrologic (or water) cycle and necessary for a healthy Puget Sound. This inflow of water replenishes our drinking water supplies, streams and wetlands.

Finding answers to the challenges posed by stormwater is not an easy task, and much is at stake, including the survival of one of the region’s most enduring icons, salmon. Recent research shows that our current practices are not sufficient to meet the challenges. What can be done to improve the situation?

First and foremost, local governments can best manage stormwater through land use planning under the Growth Management Act. Countywide planning policies that set urban growth boundaries with appropriate densities prevent sprawl and reduce impervious surfaces that generate stormwater. Adopting critical areas ordinances with adequate buffers protects streams, wetlands and other sensitive areas.

Next, a number of organizations in Puget Sound and around the nation are developing innovative practices to manage stormwater. These “low-impact development practices” should save developers and homebuyers money while better protecting the environment.

'Mother' knows best

The theory behind low impact development is simple, based on the concept that Mother Nature knows best. Trees in forests are the best stormwater facilities ever made; research shows that runoff from a forest is practically nil.

So the idea is to let nature work for us. Rather than clearing and grading an entire building site, a plan is developed that retains a portion of the site’s natural features to collect, treat and infiltrate stormwater. Some of the trees and forest, along with any important streams or wetlands, are then protected and serve as a combination stormwater facility and general open space. The rest of the site is developed, using techniques to cluster houses and buildings to still meet the project’s overall goals. Road widths are narrowed and other impervious surfaces are reduced. Developers and builders may significantly reduce their costs by not having to build expensive stormwater facilities.

Solution
Vegetative strips and other permeable pavement greatly reduce stormwater runoff. Photo by Curtis Hinman, Washington State University Cooperative Extension.

Putting policies to work Other strategies include permeable pavement for driveways, rooftop gardens and cisterns to collect rainwater, and amending soils to increase infiltration. These and other low impact development practices are part of Smart Growth strategies promoted by developers, land conservation groups and government agencies. The Urban Land Institute co-sponsors an annual conference to promote Smart Growth policies nationwide. Last year’s keynote speaker was David Williams of Atlanta’s Post Properties, one of the nation’s largest development firms.

Low impact development practices may not work on all sites. To ensure consistent standards for all new development in Puget Sound, the state Department of Ecology maintains the region’s stormwater manual. The department is currently updating the manual to include new best management practices and improved flow-control standards. Developers will have the flexibility to use low impact development practices where appropriate.

Tying all these efforts together is the job of the Puget Sound Water Quality Action Team. The Action Team is the keeper of the Puget Sound Management Plan -- the state’s comprehensive strategy to protect and restore the Sound. The Action Team is amending the plan’s Stormwater Program to provide a new vision and set policies for stormwater management in Puget Sound. A draft will be available for public review this fall.

The Action Team is also working with others, including the Washington State University Cooperative Extension and the King-Snohomish Master Builders, to promote low impact development and “salmon-friendly” building practices. Last fall the Action Team partnered with the Washington Organic Recycling Council and others to host Soils for Salmon workshops.


For more information, contact the Action Team at 1-800-54-SOUND, or visit their website.


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