Managing stormwater runoff—a major threat to Puget Sound and other water bodies — can be an expensive proposition, particularly in already-urbanized areas where the existing infrastructure may be inadequate. So it’s heartening to see the emergence of low-cost but highly-effective solutions like rain gardens.
Maria Dolan has a good article on the subject in the latest Seattle Magazine:
The rain gushing from downspouts this time of year can seem like water torture for local residents, as it puddles on lawns, spills over sidewalks and seeps into basements… But there’s another panacea that’s likely more cost-effective than all the others: a rain garden. Proof that it works? The City of Seattle, after installing test gardens, found this hydrophilic landscaping feature so effective that it will roll out rebates in March for some homeowners willing to dig in to this environmentally friendly practice.
In other words, the rain gardens are so much more cost-effective than the old gutter-and-pipe systems that the city of Seattle is willing to pay much of the cost of installing them, even on private property—at least in places where the current infrastrcuture isn’t up to snuff. (This spring, the city is rolling out a full-rebate program in a portion of the Ballard neighborhood.)
Now I’ll grant you that rain gardens by themselves are not sufficient to fully address the stormwater problems that cities face (though they may be able to put a small dent in it). But rain gardens are emblematic of a better way to deal with stormwater: low-impact development (LID) techniques. There’s mounting evidence that the green infrastructure of LID is actually more effective at dealing with runoff than the old hard infrastructure of storm drains and sewers. There’s little doubt that LID is cheaper.
One final point. Folks sometimes mistakenly conclude that densifying cities are the root cause of our stormwater problems. That’s true only in the narrowest of senses: increased impervious surface yields more runoff, sure. But, in fact, density is the very best way to reduce the total amount of impervious surface in a watershed.
Permitting low-density development into green space is the real recipe for disaster, both because it adds more impervious surface per person, often much more. It’s crucial to remember that the most effective stormwater system—bar none—is not LID. It’s what LID engineering tries to replicate: nature.