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.
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.
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…