Crowd Sourced Mitigation:
Runoff and Rain Gardens in the Puget Sound
University of Memphis
6730 Earl Ave NW. Seattle. Monsoon Rain Gardens
Seattle has long been called the Emerald City for being green. Autumn and winter rains go well into the first half of spring and work like a soaker hose to nourish the biosphere followed by the relatively clear May through September period which give plants sunlight for their photosynthesis. But "Emerald City" was in danger of becoming just a name and not its description and "The Evergreen State" - Washington's motto- was becoming less and less green. From 1980 to 2000 the metro area (which includes Bellevue, Kent, Tacoma and Everett) almost doubled in population from 1.607 million to 3.044 million. By 2010 there were 3.44 million. And the 2015 estimates 3.734 million people living in the three counties. Population plus rain equaled problems (Census )
One area that was being hurt by the growth was the waterways which flowed to Puget Sound and Lake Washington as the famous Northwest rains washed pollutants into the urban watershed. The population increase meant an increase in impervious cover every time something was constructed. The rain had fewer places to soak into the ground making what could be clean, life-giving rainwater into dirty urban runoff washing the streets of their oil, antifreeze, fertilizer and pet waste down into the waterways. It is estimated the Sound receives 14 million gallons of toxic pollutants every year ( Mittermair, 2016)
The iconic Orcas were becoming some of the most PCB contaminated mammals in the US ( Barnet , 2015). Coho salmon, treated for centuries as gifts of the heavens, ( Fobes, 1995) were not surviving the trip up King County streams ( Barnett, 2015). "The majority of our region’s Puget Sound pollution is caused by rainwater runoff from our streets, driveways, lawns and rooftops. In fact, 14 million pounds of toxins enter Puget Sound each year," according to Emma Vowels, project coordinator at Stewardship partners, an area environmental organization ( Vowels, 2017).
The Puget Sound Action Team in 2007 had a grim assessment. "The Sound's overall trajectory continues to be one of decline with harm to the clean water, abundant habitat and intact natural processes that are foundations of a healthy environment." ( Fletcher, 2008) The Sound was getting less friendly to both man and beast, giving Governor Christine Gregoire to issue a call to get the sound "Fishable, Swimmable, Digable ( Fletcher , 2008)
And there were other issues, too.
Some of the storm drain pipes designed to remove the runoff from the city were probably adequate when they were first installed but the growth made the areas less able to expedite the rainfall .( Cacho, 2017) . So urban runoff was giving the area two big problems – dirty waterways and flooded streets and basements.
But initiatives by state, city, nonprofits, business owners, higher education and civic-minded people aims reverse those trends by using the land, the greenery and the love for the environment that drew people to the area for individual based mitigation of these hazards.
The Wet Winters
A primer on weather of the area is in order. The jet streams in the winter months carry moisture from the Pacific Ocean east into the Pacific Northwest. The flow reaches the cooler land where the prevailing winds force the humid air over the mountains west of the city. The water vapor condenses into rain and snow as it passes over the mountains due both to the cooler land surfaces and to adiabatic cooling as it expands rising up over the mountains. It is worth noting that despite the rainy nature that Seattle is known for, there are mountains on the Washington Coast that receive roughly six times the annual precipitation of those two cities. And going into eastern Washington some areas average less rain than the driest spots in Texas ( Mass, 2008)