Snohomish Conservation District is partnering with King County and the city of Bothell to install a cluster of four rain gardens in the neighborhood behind Bothell High School.
Alicia Kellogg, a community conservation project coordinator for the district, said the goal is to “build momentum in the city for doing more projects like this.” Rain gardens are “cheaper and more beautiful” than other stormwater infrastructure, she said.
To get the rest of the community involved, the district will host a volunteer planting party, where it will provide gloves, tools, refreshments and a chance to win a free rain barrel. The event will be held from 4-6 p.m. on Oct. 11 at 89th Avenue Northeast and Northeast 187th Street in Bothell.
The gardens in Bothell’s cluster are being installed free of charge, except for the cost of plants, and the work is being done by the district’s paid veteran crew, along with some AmeriCorps members from the Washington Conservation Corps.
A rain garden is a landscaped area that collects, absorbs and filters stormwater runoff from rooftops, driveways, patios and other hard surfaces that don’t allow water to soak in. Gardens in Bothell’s cluster range from 110-200 square feet.
The gardens help keep storm drains and sewer systems clear of rain and stormwater runoff, which can sometimes contain pesticides, fertilizers, petroleum, animal feces and other pollutants, Kellogg said. These can eventually end up in streams, wetlands, lakes and marine waters like the Puget Sound.
“The more we can keep water on the property and let it absorb at a natural rate, the better it is for the environment,” Kellogg said.
According to the 12,000 Rain Gardens in Puget Sound campaign, led by Washington State University and Stewardship Partners, rain gardens “beautify the neighborhood, prevent flooding and fight pollution.”
There are many steps in rain garden construction, from planning to planting, but there are also readily available resources for people who want to put them in their yards, including the Rain Garden Handbook for Western Washington that can be found online.
The first step, after deciding where the garden should go, is to “dig a big hole,” Kellogg said, and remove native soils.
Rain gardens are carefully designed to achieve their goal by using spongy living soils and properly chosen plants. Bothell’s cluster of rain gardens contain a biorentention soil mix from Cedar Grove, made up of 60 percent sand and 40 percent compost, along with animal-friendly hog fuel.
Adding soil and mulch is the second step in construction, along with river rock, which can help slow down and disperse water and prevent erosion.
Then, a trench is dug to connect the garden to the drain pipe on the home. The last step is planting. Kellogg said that garden installation may seem like a lot of work initially, but over time, it cuts down on lawn maintenance. The right selection of plants, including native species and others adapted to western Washington, mean that a rain garden will need little or no watering after two or three years.
Along with educational resources, financial help is also available for people who want to install rain gardens. Snohomish Conservation District offers free consultations for people who live in the county and landowners within the King County Wastewater Treatment Division service area can apply for Green Stormwater Infrastructure Mini Grants for up to $1,500.
The district is also installing other stormwater infrastructure in the Bothell neighborhood, including rain barrels that can hold up to 50 gallons of water. It’s also working with homeowners’ associations on ways to prevent stormwater runoff and help the environment.