Recycled water serves as a vital tool to protect rivers and streams throughout Washington, especially the Sammamish Valley, as the region continues to face increasing demands and climate change stressors.
As part of an ongoing series of community education programs presented by the Sammamish Valley Grange, a panel of staff and educators provided an overview into the Recycled Water Project on Thursday, April 7. Water reuse, also commonly known as water recycling, reclaims water from a variety of sources then treats and reuses it for beneficial purposes.
“[Recycled water] is sold in grocery stores,” said Nicole Gutierrez, project associate with Washington Water Trust. “You're likely already eating produce grown by recycled water, you just might not know.”
The project seeks to expand the use of recycled water in the Sammamish Valley, which is home to some of the most productive agricultural lands in the state and the King County Brightwater Treatment Plant. The collaboration between Washington Water Trust, King County Wastewater Treatment Division and Washington State University Puyallup Extension is designed to investigate recycled water as an irrigation source and assess its safety on edible food crops.
“Our objective was to conduct an in-basin research study to address and subsequently improve perception of the use of recycled water on food crops,” Gutierrez said. “But there's not a lot of food irrigation with recycled water in Washington state. So, we wanted to provide a really localized research study for producers and consumers to understand the associated risks of irrigating with it.”
To conduct an in-basin research study, the parties involved built a research garden along the Sammamish River Trail to assess the impact of using alternative water sources on specific vegetable crops. According to Gutierrez, using recycled water for irrigation would reduce river diversions while protecting salmon and other wildlife that depend on cool and clean water.
The Sammamish River supports a variety of salmon species, such as chinook, coho, kokanee, sockeye, steelhead and coastal cutthroat trout. Just because the salmon are present, Gutierrez noted, does not mean they are thriving.
She said the project is also dealing with water issues linked to in-stream flows within the Sammamish River, which contribute to water temperature concerns and dissolved oxygen. There is a growing demand for water resources in this area as well as throughout Washington state due to population growth, which can be exacerbated by climate change conditions, she added.
Two goals at the forefront of the water project are related to outreach efforts and the study design. Gutierrez said outreach consisted of evaluating perceptions and concerns along the food supply chain in the Sammamish Valley, which extends to restaurateurs, grocers and consumers. With a better understanding of concerns from producers, the project team was able to implement a study design to evaluate the impact of recycled water compared to a more typical irrigation source for food crops.
Ed Kolodziej, associate professor at the University of Washington, has been measuring chemicals within the Sammamish River recycled water. He said contaminants of emerging concern, otherwise called CECs, get into water from pharmaceuticals, personal care products, flame retardants, detergents and other industrial chemicals with potentially significant impacts on the environment.
“We're always surrounded by chemicals at all times. Everything is chemical in some fashion,” Kolodziej said. “Chemicals enter the environment in some fashion, whether that's a wastewater treatment plant or the septic system at your house or something else like that.”
Kolodziej said CECs are present in water, air, soil, plants, fish, and inevitably, food crops. For the last 20 years, he noted, people have tried to understand what these contaminants mean for humans, fish and the environment as a whole.
“These chemicals have been around for decades, and it was only until recently that we were able to measure them with analytical abilities,” he said. “I always think of the environment as like a gauntlet for chemicals.”
The team took on a list of 206 different CECs from the demo garden along the Sammamish River to evaluate as part of this project, Kolodziej said. Some of the contaminants include pharmaceuticals, antibiotics and personal care products.
To conduct this research, the team selected kale and carrots as two plants that are considered to be the highest potential for uptake of CECs and other chemicals present in the water. These plants are also grown in the valley, and that was another driver for the plant selection.
Carrots, which represents the below-ground biomass, will tell the researchers what CECs can enter roots. Kale, as a representative leafy green, will determine what CECs can move up into the leaf.
Kolodziej said a project website will soon be available online to share research results.