Garden Variety

How Your Yard Can Protect Puget Sound

A little landscaping can help curb a major source of pollution in the Salish Sea.

By Benjamin Cassidy December 13, 2021

A rain garden outside a Ballard home

Jenny Ngo didn't mind if her first front lawn was on the wild side.

Digging a ditch in one’s yard tends to raise some questions. When a couple of workers shoveled soil from the front lawn of Jenny Ngo’s recently purchased Craftsman, chunks of sod piling up along the hole’s perimeter, neighbors didn’t hesitate to ask a few. “I think there was a joke of like, Are you guys putting a hot tub out front?” the Ballard resident recalls.

No, David Hymel and Marilyn Jacobs of Rain Dog Designs patiently responded, they were doing what they’d been contracted to do for more than a decade across the Puget Sound region: build a rain garden. The landscapers work with RainWise, a Seattle Public Utilities and King County Wastewater Treatment Division program that offers rebates to homeowners who install these bowl-shaped, environmentally friendly plots on their properties.

It’s an increasingly vital form of landscaping. In our slick city, pollutants far from the water’s edge still seep into the Sound. Downpours transport toxins from roofs, driveways, and streets into urban streams that feed our most renowned body of water. This stormwater imperils marine life. Researchers recently found that tire dust was a primary culprit for the deaths of coho salmon returning to the area to spawn. By capturing chemicals before they reach waterways, absorbent rain gardens can seed the recovery of the region’s most embattled fish. “There’s such a need for this right now,” says David Burger, executive director of Stewardship Partners.

The nonprofit’s long-running “RainChangers” campaign to plant 12,000 rain gardens across the region has trickled down over the years from schools and other institutions to homeowners’ yards (Pearl Jam guitarist Stone Gossard, for instance, has a second rain garden in the works on his land). While only certain homes in sewer overflow basins are eligible for the RainWise cistern and rain garden rebates, Stewardship Partners offers grants of up to $4,500 for others in the area who want to install them. Its tracker can’t account for all the interest, according to Burger. “They’re popping up everywhere.”

Ngo knew she wanted one when she and Brian Knox bought their Ballard home off-market in late 2020. The King County Council analyst had previously worked as a city planner and helped produce the local handbook on rain gardens years ago.

Rain Dog Designs was one of RainWise’s first approved contractors. After testing to see how fast the water soaks into the ground, the landscapers consider the garden’s placement—anything less than 10 feet from the foundation risks flooding the basement. The size of the plot they create depends on the property; RainWise refunds $4 for every square foot of rooftop runoff. Ngo says the rebate covered $5,800 of her rain garden’s $7,200 cost. 

The out-of-pocket expense deters some eco-conscious homeowners from excavating their lawns, Hymel notes. Others are skeptical of the aesthetic. Ngo remembers her parents worrying about standing water in front of her first home. It would have to be strategic, she observed.

Hymel and Jacobs are exacting. They typically dig 24 inches into the soil, replacing it with an 18-inch mix of compost and sand. During the week or so process, they bury rain piping from the roof and create a rocky area to stem overflows from ponding water.

The final product isn’t just a mass of mulch. Ngo dotted her terrain with blue fescue, sedges, succulents, Russian sage, and dogwood, among other varieties of plants. “If they get a little wild,” says Ngo, a nascent gardener, “it would just be part of what a beautiful Seattle yard should look like.”

The neighbors aren't so skeptical anymore. After they were done working on Ngo’s property, Hymel and Jacobs built another rain garden right next door.

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