CrowdSourced Mitigation:

Runoff and Rain Gardens in the Puget Sound

Devin Greaney

University of Memphis

Spring, 2017

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. Clean, life-giving rainwater became 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 PCP 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 or  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)

Aberdeen Reservoir  130.6"

Bellingham  35.83"

Bremerton  56.37"

Everette  38.44" 

Mt Vernon  33.20"

Olympia  50"

Renton  40.05"

Seattle Boeing Field  39.88"

SEA TAC Airport  37.49"

Tacoma  39.22"


What is not common in the area are sudden thunderstorms or flash flooding. Generally flooding is a more gradual process like the disasters that hit Oregon City on the Willamette River South of Portland  in 1964 and 1996 . (Greaney, 2010)

The Hanukkah Eve windstorm December 14, 2006 flooded out the low-lying streets of Seattle, but particularly tragic was the area known as Madison Valley south of Washington Park, West of Lake Washington. Historic flooding, a low lying area that was once a creek and the lowest point in the neighborhood  all came together at Kate Fleming and Charlene Strong's home.

Fleming and Strong lived at 30th Ave East and East Mercer Street. Fleming, a voice actress, saw the basement flooding, and went to rescue her recording equipment. Flood waters burst through drain pipes, trapping her. Strong attempted a rescue while calling the fire department. Firefighters cut through the floor, pulled Fleming from the basement and transported her  to the level one trauma center where she died shortly afterwards. ( Rowe, 2006 and Strong, 2017 )

Her death was not typical for the area. A NOAA database that goes back to 1996 shows no other flood deaths before or since this incident in King County, (NOAA)  but an engineering firm was hired to investigate why there was a flood especially one that killed and killed a Seattlite in her basement.  The study concluded the drainage was inadequate. ( Berger, 2007)

Fixing the problem

Writer Cynthia Barnett referred to the "20th century course of channelizing rivers and importing waters long distance as local rains flush to the sea" (Barnett , 2015 p 240) as a mentality that she identified with Southern California but can be found most anywhere. Excess water was to be expedited out of a region while drinking water was to be brought in partially because the rain never had the option to soak in and replenish the groundwater. The first  photo below shows a creek in East Memphis paved in the 1950's, the  second photo shows a section of the same creek between Cole Rd and Mendenhall that was reshaped and repaved in 1978-1979 to allow more drainage after overflow was ending up in yards.

Most of the area was developed in the early 1950's or 1960's where this East Memphis creek was paved between Cole Rd and Fairfield Circle.  Feb 19, 2017. Devin Greaney.

The 1979 repaving between Cole and Mendenhall. Photo Feb 19, 2017 Devin Greaney

Notice the still well-paved ditch despite more than 50 years. The second image shows little wear and tear after over almost forty years of carrying rainfall. Based on both the MidSouth and the Puget Sound areas being wet climates with similar winter temperatures ( Mass, 2008)  one could presume a similar ditch in Seattle taking King County runoff to the Green or Duwamish Rivers then to Puget Sound would have been subject about the same amount of stress as this ditch taking waters to the Wolf River then to the Mississippi. The point is once impervious drainage is in place, removing it is difficult.

Building more drains to pull the water quickly away used to be the obvious choice to keep an area from flooding. But any intro to emergency management student will tell you those days are gone when engineering irrespective of the environment to build a way out of a problem were considered ideal. Working with the environment has shown itself a more effective way to keep lives and property safe. Drains have their limits and move the waters elsewhere where flooding may again take place.

Neighborhoods unable to drain themselves and a flow of dirty runoff into the Sound and Lake Washington gave an impetuous from local government to give grants to home and business owners in the area if they would either build rain gardens or if they were in an area with drainage issues or install cisterns.  While most hazard mitigation is thought of as top down – dams,  levees,  purchasing land on the flood plains- here this was aimed at the home and business owners to create a first-line defense in keeping the waters clear and basements dry.

In cities a raindrop hits the impervious surface, joins other raindrops  and flows to the lowest point becoming runoff. It carries with it the byproducts of the city to the lowest point, in this case the sound and the lakes.  In the natural environment there is still some runoff but most of it soaks into the ground instead of flowing away. In the forest decayed plant matter becomes loose soil that allows water to percolate into the  groundwater table or be soaked up by the vegetation to be used by the tree then returned to the air through evapotranspiration.

The rain garden attempts to recreate the latter in the world of the former.

In a rain garden an area is dug out. It is recommended the Sight not be on a steep slope, within 10 feet of a structure or over a septic system.  On the bottom gravel lines the surface of the garden. The over the layer of rock is sand then loose compost soil. Planted in the garden are plants that take water yet are not designed to live in water as this is still a garden, not a pond or wetland.  It also helps to put the garden not in a stream bed but an area where it can receive much of the water flow such as near a rain spout. 

In 2010 the Rainwise program was introduced by the City of Seattle to the public to encourage the use of rain barrels, cisterns and rain gardens to reduce runoff. "It’s a retrofit program. It's not for new construction we have our stormwater codes for that," said Laura Cacho senior program manager at Seattle Public Utilities. (Cacho,2017) "The funding is for reducing combined sewer overflows in parts where the piping is combined so the sewer and storm water flow together. Those are areas where we have if we have big rain storms often our pipes cannot handle and the water overflow and flow into the lakes or Puget Sound. " A map shows areas where residents and institutions are eligible for grants. "It's less based on topography and more based on the infrastructure serving that property." (Cacho, 2017)

There are grants available as long as they are in the area, use an approved  contractor and the property is appropriate for a rain garden. Not all places are but SPU offers cisterns which hold the water temporarily to slow the flow of the rainfall. Rain gardens do that as well but the gardens have the added benefit of infiltrating the water into the soil or releasing it through evapotranspiration rather than just releasing it slowly so rain gardens are given a higher rebate amount.  " We have a lot of topography challenges we have a lot of really steep hills and a lot of steep slopes that are not appropriate for a rain gardens,"  Cacho said. ( Cacho, 2017)

In the private-nonprofit sector a local environmental group Stewardship Partners has been encouraging the use of rain gardens since 2008. Unlike the perfectly groomed gardens often seen in front yards, rain gardens can have a look of a wildflower meadow and work to manage the rainfall. In 2011 the group teamed up with Washington State University Extension in 2011  starting a movement and website called 12, It gives education on how they work, how to build them, how to get area incentives and an interactive map to show where these gardens can be found. 

"By combining our experience in building and educating about rain gardens with WSU’s preeminent stormwater research and unparalleled community access through its Master Gardener programs in each county, this unique team created a network of community-based rain garden resource hubs all around Puget Sound," Vowels said. ( Vowels, 2017)

Hazard mitigation is perhaps most often associated with large government projects such as the ditch work seen in the earlier photos or regulation of homes and businesses.  But this has more of a ground up sense than a typical public works infrastructure project. "Homeowners have felt stronger ownership of the 12,000 Rain Gardens Campaign because we help them become the agents of change in their own communities,  as opposed to forcing regulation on them from the top down. We provide the tools that homeowners need to install a rain garden or cistern which will both benefit their property and the health of Puget Sound," Vowels said. ( Vowels, 2017)

The goal was to hit that number in five years however a check this Spring shows they have reached about a third of the goal. ( However keep in mind some areas do not work as well for rain gardens others due to the slope of the land and other factors.  ( Vowels, 2017)

Almost all areas of King County are home to stormwater mitigation. Stewardship Partners

The Rain Garden

"The object is to keep the water from flowing into the nearest body of water," said journalist and passionate gardener Emily Green of Baltimore. "Depending how much rain, you need to grade it with in ingress in egress. Once your garden becomes saturated flow out and continue down whatever water course it's going to continue down be at an alley or stream" ( Green, 2017)

Rain Garden illustration. Please note there is a 6-12" depression to temporarily hold rain water but that water usually soaks into the soil in about a day. Washington State University

While living in Southern California her goal was to capture all the rain that fell and reuse it either in her garden. Besides the use of rain gardens, cisterns and rain barrels ( which are smaller water collection devices) are part of her design. ( Green, 2017) 

"It requires looking how the natural system works and engineering with that natural system. Every single time you'll get the best result working that way," she said. (Green,2017) But Green advised there needs to be consideration in how  practical such plans may be and consider human nature as well. In Baltimore the program advises residents with rain barrels or cisterns to bring them inside during the winter. "They expect people to disconnect them and drag them inside and throw them in their basement to avoid frost damage in the winter. I wonder how many people who do that who aren’t as eccentric as I am," ( Green, 2017) "The minute you have these wrinkles that expect this eccentric and obsessive behavior, I think you're looking at something that won't work. I think it has to be a kind of system that works with the natural flow of events." (Green,2107) 

Native plants, particularly ones that can tolerate long periods of dryness and heavy rains are recommended for planting ( Memphis Shelby County nd) .


The Pacific Northwest has little in the way of mosquito problems ( Ahearn, 2014) but in the warmer moist areas mosquitoes are an issue and that is part of the reason runoff is quickly sent from the streets to the storm drains. Ture Carlson, entomologist for the Shelby County Health Department said it takes seven days for a mosquito to go from egg to larvae to  flying insect. " If there is a guarantee that the rain garden will be 100% dry within 5 days then there is not issue with mosquitoes but that guarantee can be weather dependent because if it rains every couple of days the constant supply of water can become the issue," he said. "Any time water will be present for at least 6 days (typically it is 7 days but I like to take one away just to be safe) mosquitoes are a concern, and especially any shallow water that does not contain fish." ( Carlson, 2017)

Gardener Emily Green says rain infiltrates into the ground within a day or two in a well-designed rain garden long before larvae take to the air. "It's very unusual to have standing water," she says. The problem she sees is old tires, trash cans and flower pots that have collected water. "In almost any garden in the area I can find about six places mosquitoes can breed" she says. She also uses rain barrels which hold about 50 gallons but are designed with mosquito nets. "If you leave standing water and the mosquito has any access at all they’ll breed. I don't recommend leaving them full. I always flow them in the garden. The best place to store rainwater Is in the soil," ( Green, 2017)

Speaking of Memphis, The Memphis and Shelby County office of Sustainability has both and a guide to install them on their website. Volunteers installed a rain garden at the Peggy Edmondson Building at 1075 Mullins Station June 20, 2015. A visit by this writer in early 2017 shows the gardens are still at the site. ( Memphis Shelby County Office of Sustainability n.d. )

The State and the  Science and Education of Runoff

The state is also involved in mitigation. A publication gives homeowners and  The Washington Stormwater Center is a state-mandated research & learning center for stormwater at Washington State University- Puyallup which is east of Tacoma ( McIntyre,2017)

Early studies of the effects of something similar to a rain garden have shown strong promise.  Coho salmon tend to swim upstream from the Sound  in the November when the rainfall was at its heaviest and were dying within a day when reaching (supposedly) fresh waters. . Taking actual urban runoff from a Seattle area Interstate highway and subjecting the fish to the waters showed almost without a doubt that within the mystery of why the coho were dying the culprit was the urban water flow washing into King County creeks. ( Doughton, 2015)  Dr Jenifer McIntyre, Professor of  Aquatic Toxicology at Washington State University,  referred to the  "crazy complex cocktail of chemical contaminants" which are transported by runoff. ( WSU , 2016) Researchers noticed all of the fish placed in the runoff water died within twelve hours.  In addition there were delayed developments of the fish embryos raised in storm water in comparison to filtered water. "That happens when an animal spends a lot of energy trying to detoxify its body." ( WSU,2106). The researchers added oxygen to the runoff water and it still did not save the fish.  But there was another side. 

McIntyre said "It was absolutely remarkable" ( Doughton, 2015) to see the results of a related portion of the experiment. The  storm water- the same water that killed the fish- was filtered by the team through sand, soil and compost similar to what would be found in a rain garden and none of the fish died within 96 hours, none  had gotten sick and only differences found were signs of residual toxicity in smaller fish used in research though even in those fish there were no illnesses detected. She emphasizes low impact development may be one area to alleviate these problems of the salmon mortality.  (McIntyre, 2016) ( McIntyre, 2017)

In addition the State of Washington has reached out to the public with a guide to rain gardens ( Washington State, 2013) and education and partnering with the films "Polluted Puddles: Arlo's Quest to Clean up our Mess" (Shaw, 2017) aimed at elementary school students and for junior high and high schools there is "Lost and (Puget) Sound: How we followed the Rain and Found Our Voice." ( Darev, 2011)

The former gives a simplified version Washington Stormwater Center experiment in a way children could understand. The latter ends with a rallying cry of different Seattleites saying their name, their community "and Puget Sound starts here." It’s enough to make anyone want to move to Greater Seattle and work for Dr McIntyre's lab as her personal assistant. 

Lost and (Puget) Sound: How We Followed The Rain And Found Our Voice from Inye Wokoma-Ijo Arts Media Group on Vimeo.

Seattle Public Utilities

Polluted Puddles: Arlo's quest to clean up our mess from Washington Environmental Council on Vimeo.


High Point Redevelopment sought to restore more impervious pavement into much of a neighborhood, getting rid of the traditional pavement into pavement where the rain and snow can soak into the soil rather than flow into nearby Longfellow Creek. So though de-paving has been minimal, permeable pavement has replaced concrete and asphalt in a number of those areas which further adds to minimizing runoff. ( Seattle, 2015)

An inquiry to Seattle Public Utilities shows this is an active part of flood and water pollution mitigation in other places as well. One of the more  ambitious ones is Thornton Confluence floodplain in the Northeast section completed in 2014 which replaced an aging culvert and returned 2 flood-prone acres to a more riparian state. Four homes were purchased and razed for the project ( Fugger: 2017) 

Other Civic Projects

There is more than just a reach out to area homes, businesses and churches to mitigate these issues. Stewardship partners has a library online and has looked to municipalities to ask about their stormwater management. "Some cities that are in fairly well-developed suburban areas responded by simply saying that their municipality does not collect that type of data. Meanwhile municipalities that I would not have anticipated to have strong stormwater management programs were glad to send handfuls, if not more, of rain gardens or bioretention facilities around their cities," Vowels said ( Vowels, 2017)

  Center for Watershed Protection

In the Spring of 2001 under a program called Street Edge Alternative (Seattle SEA),  two blocks of NW 2nd Avenue was designed in a way that reduced impervious surfaces. Added planting and changing the shape of this street which did not have sidewalks plus adding. Engineers say they reduced runoff by 97 percent.  (Mantuso, 2001)


Seattle is not perfect. February 9, 2017 rains overwhelmed the area and King County's West Point Water Treatment Plant was forced to release 440 million gallons of sewage per 24 hour period into the sound about ¾ of a mile from Discovery Park, 240 feet below the surface ( Demay, 2017) 

Pollution and flood control, Seattle shows us, can be equally utilitarian and beautiful and rain gardens in the area have become nothing short of works of art. In the  Madison Valley area two large parks each about half the size of a city block have been constructed.  The first was finished in 2009 at 30th and East John. It has walking paths and is a focal point for the established neighborhood. The other finished later is in the 3000 block of Madison with ball fields and a walking path that leads into the Arboretum area of Washington Park. Both are built of landscaping that any landscape architect would be proud to show off in a portfolio and neighbors proud to show off to visitors. But upon closer inspection these are very large rain gardens with storm drains. ( Pailthorp, 2013). The gardens are like the smaller ones in the area designed to hold or slow millions of gallons of runoff before sending the water downstream or into the soil. At one of the two parks, the one closest to the site of where her home once stood, is an 8-foot-tall granite memorial to Kate Fleming, the actress, who might have still been alive had those improvements had been installed before the flood and saying her oft-repeated original quote she would repeat before a performance, now etched into the memorial. 

"Be a light. Be a flame. Be a beacon."  ( Barnett, 2015 p 237 )

Devin Greaney is an Emergency Management Major at the University of Memphis

Here he is on the Bainbridge Island Ferry in a 1991 trip to Seattle.


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