A stroll down a stretch of 2nd Avenue Northwest in Seattle is practically a walk in the park. The slightly meandering residential street is lined with wide strips of native grasses, small shrubs, and trees. Along the shoulder, interspersed among parking spots, are ponds and swales – gentle depressions – that fill with water during a downpour. What you won’t find are sludgy gutters brimming with muddy water and trash, or deserts of black asphalt stretching from property lines to the roadway.
The street was the city’s first experiment in what it calls “natural drainage systems.” A decade ago, the block was jackhammered up and rebuilt to catch and clean stormwater the way it’s done in a forest: by helping rainstorms soak into the ground, get sucked up by plants, or captured in their branches and leaves where the water evaporates slowly. The project -- called SEA Street -- has been wildly successful, nearly eliminating stormwater runoff even during heavy rains. That's right, runoff on this street was reduced 98 percent during winter rains.
Natural drainage systems are cropping up slowly on streets across Seattle. And other Northwest cities are doing similar projects to curb runoff without pipes and holding tanks. The city of Portland even has an "ecoroof" blog site geared toward innovative stormwater solutions. Vancouver, BC, is building rain gardens at bus stops, among other projects. It’s all part of a movement called “low-impact development” or LID.
For years we’ve known that traditional infrastructure for funneling stormwater away from buildings and roads and into lakes and bays by using pipes and ditches doesn’t work. It fails for people: the systems are regularly overwhelmed, leading to flooded basements and raw sewage pouring into public waterways. It fails for nature: salmon and other species are poisoned by the polluted stormwater and quiet streams are transformed into torrents of filth.
The logic of LID is to try to replicate what Mother Nature does naturally by using engineering tricks and limiting sprawl.
Washington is at a crossroads for low-impact development. The state Department of Ecology, working with a technical advisory committee, is crafting a set of requirements specifying where and how to use LID. The stakes are high. If Ecology comes up with stringent standards that require widespread use of legitimate LID strategies, Puget Sound could reap great benefits. If it doesn't, the fight to save the Sound could be lost due to the steady drumbeat of destruction from stormwater.
"Time is not on our side," said Tom Holz, a stormwater/LID expert who's on the advisory committee. "We may lose the battle just simply through dallying."
Dealing effectively with stormwater requires a two pronged approach:
1.Stop sprawl -- In an undeveloped setting, stormwater is essentially non existent. The best way to reduce runoff is to minimize the footprint of development.
2.Use low-impact development -- When development does happen, it must be LID. Already built neighborhoods should be retrofitted over time using LID techniques.
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