Who’ll Stop the Rain?

Whether falling in a mist or a torrent, the Northwest’s rain is familiar and dependable. But as rainwater streams off roofs and across pavement, it picks up a toxic cocktail of substances such as chemicals to remove moss, crank case drips and lawn pesticides. Polluted stormwater runoff is the leading source of hazardous chemicals entering Washington’s largest body of water, making oysters and clams unsafe to eat, and sickening the region’s endangered orcas.

The volume of stormwater is staggering. With a heavy downpour, the equivalent of 10 bathtubs of rainwater streams off the roof of a typical home in the Puget Sound area. During a year, that’s 26,600 gallons of water gushing into gutters and storm drains from each house. In extreme cases, these deluges fill basements knee deep in muck, erode hillsides and wash out roadways. Heavy rains overwhelm sewer systems, flushing untreated sewage into public waterways.

So if Puget Sound is facing an environmental crisis, the rain is partly to blame.

Of course, it’s not the rain’s fault. The real problem is how we’ve built our highways, homes and businesses to handle the wet weather. For more than a century, our civil engineering goal has been to funnel the rain from roofs and roads into pipes, then sluice it into rivers, lakes and bays. To solve our stormwater woes, we can turn that whole notion on its head.

Instead of speeding the downpours into gutters and pipes, we can capture and hold the rain where it falls, so it never has a chance to wash toxic substances into our waterways. “Low-impact development” or LID helps the rain soak into the earth using technologies that mimic nature. That concept means building stores and homes capped in eco-roofs that are blanketed with soil and plants that absorb the rain. It means designing properties that are landscaped with rain gardens—shallow depressions lined with sand and rocks that absorb precipitation. It means paving sidewalks and parking lots with porous concrete that lets rainwater percolate through to the ground below.

Fortunately, because pipes and gutters are so expensive, LID saves money while it spares our natural heritage. A national study of stormwater projects calculated costs for LID techniques compared to  conventional gutter-and-storm-drain systems. In 11 of 12 cases, LID was cheaper, and by 15 percent or more. In some cases, LID cost only a fifth as much.

In the case of Seattle’s Markey Machinery Co., for example, installing traditional stormwater infrastructure at its facilities in south Seattle would have cost $1 million. Instead, the maritime company built a huge rain garden that cost less than $100,000. In a recent study, the city of Portland found that eco-roofs save money over the long term, when compared with conventional roofs, because they last much longer and because they provide added insulation, reducing heating and cooling costs.

Sooner rather than later, low-impact development will become the rule instead of the exception. This fall, the state Department of Ecology plans to release a draft permit establishing when and how LID must be used in the region’s largest cities and counties. Seattle is expected this summer to approve its own LID rules.

Shifting to low-impact development is a challenge that Northwest employers are well-equipped to meet. The region is known for its green trailblazers, from Starbucks’ commitment to recycling to Mc-Kinstry’s rise to national fame for helping businesses conserve energy. During the past two decades, Washington’s businesses have made great strides in cutting their pollution, slashing the amount of toxic chemicals released through smokestacks and drainpipes by half.

Clearly, there’s a strong track record for successful environmental initiatives in the Northwest, and the transition to low-impact development presents an opportunity for businesses and industries to both save the Sound and the bottom line. 

Alan Durning directs the Sightline Institute in Seattle. Sightline is the Northwest’s sustainability think tank. Its mission is to make the Northwest a global model of sustainability—strong communities, a green economy and a healthy environment. Sightline editor Lisa Stiffler contributed to this column.

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