King County’s wastewater ‘parks’ offer a dose of nature, minus the crowds

King County is home to many great parks and places to enjoy the outdoors. Perhaps lesser known among them are the hidden gems of nature tucked within the county’s wastewater treatment facilities.

It can be grubby work, turning all of the wastewater people send down their toilets and drains into clean water. Much of that work happens underground— and out of public view.

Above ground, though, our facilities at the King County Wastewater Treatment Division (WTD) are being designed and upgraded to incorporate open spaces supporting wildlife habitat and public recreation while celebrating local culture and the arts.

These innovative facilities prove that water treatment infrastructure doesn’t have to be all pipes and pumps. We can effectively manage pollution in partnership with nature’s cycles to help local communities and ecosystems thrive together.

These places are open to the public and usually less crowded than the typical park. They also offer quick access to abundant greenery, environmental education, art, and outdoor recreation.

If you’re looking for new ways to explore the outdoors in King County, consider an underrated venture onto the grounds of wastewater treatment facilities. One quick safety note: For the best experience please stay within designated public paths and areas!

Waterworks Gardens at South Plant

Located in Renton next to the South Treatment Plant, Waterworks Gardens is designed with water in mind and for people of all ages.

Find yourself touring the “rooms” of this lovely garden as though it were a human-sized fairy house. Its leaf-shaped ponds, marshy wetlands, and mosaic stone pathway— laid to reveal the grates beneath it—all treat stormwater runoff and demonstrate the way our vigorous water cycle works.

Next door, South Treatment Plant is a powerhouse to more than 800,000 people in Auburn, Kent, Renton, Bellevue, Issaquah, and Sammamish. It can treat between 90 and 300 million gallons of wastewater per day, depending on the weather and season.

The ponds and marshes of Waterworks Gardens are a value add to the environment, as they filter and clean the stormwater coming from the treatment plant’s 50 acres of roads, parking lots, and hard surfaces. So is South Plant’s recovery of biogas sent to the electrical grid, and creation of Loop biosolids for use in forests and farms. More info about Waterworks Gardens here.

Brightwater’s community center and trail system

No roundup of King County’s wastewater recreation spots would be complete without a mention of Brightwater Treatment Plant’s natural area north of Woodinville.

The 70-acre grounds surrounding the treatment plant host 3 miles of trails through lush forest, meadows, wetlands, creeks, and ponds. The habitat serves as an outdoor classroom and provides opportunities to spot birds, frogs, fish, river otters, beavers and deer living among the grounds.

Families, lifelong learners, and the unstoppably curious will want to drop by the Education and Community Center to learn about environmental stewardship in an interpretive clean water facility. You can find programs and events year-round on our website.

Brightwater’s public art collection is vast and celebrates the transformation of wastewater as it travels through the process of purification surrounding the treatment center facility. Find community-themed art at the Education Center or take an art walk and experience the interactive displays along walking paths throughout the landscape.

There is truly something at Brightwater for everyone with its abundant natural beauty and built environment, made for community and connection.

Please respect the landscape and other visitors by always keeping your dogs on leash and following the Brightwater Center rules. The grounds are open to the public every day from dawn until dusk with parking available, including electric vehicle rechargers! A trail map is available here.

CSO Treatment Facilities

WTD works hard to keep Puget Sound and other waterways clean. Combined sewage overflows (CSOs) date back nearly a century as part of Seattle’s original sewer system. The CSOs combine stormwater and untreated wastewater into one pipe that sends the flow out to Puget Sound during big rainstorms to prevent sewage from backing up into people’s homes and businesses.

To protect public health and the environment, WTD is preventing overflows at these CSOs by building the infrastructure that can contain and clean the dirty water at nearby CSO treatment facilities.

The story doesn’t end there, though. WTD has been enhancing these CSO facilities with restored landscapes that also put people, and art, center stage.

Rain Gardens galore near Barton Pump Station, West Seattle

Have you ever wanted to learn more about rain gardens? Visit the Sunrise Heights and Westwood neighborhoods of West Seattle to find 91 distinct roadside rain gardens; each outfitted with a unique arrangement of greenery that has an important job to do. They were created as an extension of the Barton Pump Station project in 2015.

Not only do these 15 blocks of abounding street-end greenery make for a scenic stroll, but they are a product of highly tested engineering that serves an incredible purpose underground. Here, a combination of proper soil, drainage tools, and selected native vegetation controls over 13 million gallons of stormwater each year by capturing and filtering excess rainwater.

You’ll find educational signage among the gardens offering an introduction to how the larger system works.

A journey to the beach at Murray Wet Weather Facility, West Seattle

The Murray Wet Weather Facility is an underground storage tank across the street from Lowman Beach Park in southwest Seattle. The facility helps prevent 5 million gallons of untreated stormwater and wastewater each year from discharging into Puget Sound.

It also provides more than 3,500 square feet of public space, thanks to community participation in the facility’s above-ground landscape design. With a green roof hosting a public viewing area of the Puget Sound, a walkway along a rain garden, and landscape restoration to Lowman Beach Park, this space is a scenic part of the journey to the beach and around the park.

Where the pipes meet the bay at Denny Way Regulator

The Denny Way/Lake Union Regulator manages the sewage flows crossing long distances in Seattle. It also reduces untreated combined sewer overflows into Elliott Bay and Lake Union through a large storage tunnel under Mercer Street. If that tunnel fills, the flow goes to a nearby CSO treatment facility.

A scenic plaza marks the site where the project’s pipes discharge treated, clean water into Elliott Bay. The artist-designed plaza features an integrated sculpture art and graphic imagery called Undercurrents, used for community gatherings and small performances during festivals. The stainless-steel swale takes on the form of utility and art, as etched phrases and graphic imagery describe how it carries rainwater into the bay below.

Coming Soon: Georgetown Wet Weather Station

The highly anticipated Georgetown Wet Weather Station, a CSO control project focused on protecting the Duwamish River from pollution during storms, has made it through its first winter. It has already cleaned millions of gallons of polluted stormwater runoff that would have otherwise flowed directly into the Duwamish River and Puget Sound.

Up next is the art. The station design will feature audio-visual art, including an installation that will light up the facility as water moves through the treatment process so that the community and passersby know when it’s in operation. Another art display will recreate the most recent rain event inside a 35-foot-high clear cylinder as a recorded memory of Seattle’s weather.  More on the artwork to come!