‘Kidneys of the Earth’: Wetlands filter and cool Wash. Co. wastewater

Special Reports

The Fernhill Wetlands in Forest Grove is more that just a pretty place. It also helps purify wastewater

FOREST GROVE, Ore. (KOIN) — The Fernhill Wetlands in Forest Grove is a sanctuary for wildlife, a wonderland for birdwatchers, and a hands-on learning site for kids. But this tranquil, seemingly natural area also serves a greater purpose: it’s filtering and cooling water that eventually makes its way into the Tualatin River. 

“I do love wetlands and they are the kidneys of the Earth,” said Jared Kinnear, recycled water program manager for Clean Water Services. “They slow water down and they filter out pollutants.” 

In 2014, Clean Water Services, which cleans wastewater in Washington County, transformed 90 acres of old sewage lagoons into treatment wetlands. Now, seven years later, the site continues to serve the same purpose. 

The water in the wetlands goes through an initial purification process in Clean Water Services’ Forest Grove treatment plant facility where things like nitrogen, ammonia and phosphorus are removed. It also goes through screens to remove inorganic materials.

The Forest Grove Water Resrource Recovery Facility sits right next to the Fernhill Wetlands in Forest Grove. Photo taken Aug. 9, 2021. (KOIN)

Then, in the wetlands, the plants get to work.

“The plants are designed to block the sun so that wastewater doesn’t heat up,” Kinnear explained. 

He said the plants conduct what’s called evapotranspiration, a process in which water is transferred from the land to the atmosphere by evaporation and by transpiration from plants. 

The evaporation helps lower the air temperature near the wetlands at night, Kinnear said. 

Water temperature has been a major concern in Oregon. When water is too warm in rivers, it can harm salmon and other native fish populations and can create an environment for harmful algae blooms. 

Kinnear said when wastewater comes out of a treatment facility, it’s still fairly warm. He said filtering it through the wetlands polishes the nutrients in the water, ensures the water has enough dissolved oxygen and gives it time to acclimate so it’s ready to flow back into the river. 

The Fernhill Wetlands cool and treat wastewater before it enters the Tualatin River. Photo taken Aug. 9, 2021. (KOIN)

He said about 5 million gallons of water a day flow through the wetlands and into the Tualatin River. 

“I sort of look at it as there’s like a new tributary to the upper Tualatin and that’s from the wastewater treatment plant through Fernhill Wetlands, into the river,” Kinnear said. 

If Clean Water Services hadn’t decided to construct the wetlands, it instead would have invested $35 million in 2009 into expanding the Rock Creek Wastewater Treatment Facility. The facility would not have the capability to cool the water temperature like the wetlands can. 

Kinnear said the wetlands project cost about half of what the expansion project was expected to cost, plus it cools the water. 

“It’s a very engineered system but we wanted it to look like it had always been here,” Kinnear said. 

The project focused on planting diverse native vegetation to make the area look like a natural wetland. 

A blue heron sits on a post in the Fernhill Wetlands on Aug. 9, 2021. (KOIN)

Now, a wide variety of birds and other wildlife call the wetlands home, and people visit the site daily to walk or jog the path that encircles the lagoon. 

The Tualatin River is Washington County’s primary water source. As the county’s population grows and as climate change continues to affect water sources, Kinnear said he fears the region won’t have enough snowpack to get through summer. 

He said people will need to start thinking about how they use water and how to recycle wastewater if they hope to have enough to go around in the future. 

“Water is not a renewable resource,” he said. “Trees, you know, we can go and plant more trees and have more trees for the future but what water we have on Earth is what water we have on Earth.”

He hopes the wetlands will educate people more on the purpose of recycled water. He’d like to see recycled water, rather than drinking water used more often for irrigating things like golf courses and parks. 

“We got a long way to go, but we’re making strides,” he said.

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