Recent regulatory changes from the Department of Ecology (DOE) have paved the way for local jurisdictions to use reclaimed water for a number of uses in the state.
Reclaimed water is treated sewage and wastewater that is purified to a level where it can be used for purposes other than drinking, including watering lawns and recharging groundwater reservoirs.
It can additionally be used for replenishing wetlands, increasing water flow in streams and rivers and to control dust.
In order for municipalities to use reclaimed water for the approved uses, they must obtain a permit from the state.
The rules passed by DOE establish a uniformed set of reclaimed water standards throughout the state.
A spokesperson for DOE said King County had not approached their agency to use reclaimed water to recharge groundwater aquifers.
At a Jan. 16 meeting, the Redmond City Council approved interim regulations banning the use of reclaimed water for a year to protect the city’s aquifer recharge area.
An aquifer supplies groundwater to five shallow municipal wells that pump 4 million gallons of water daily and supplies up to 40 percent of the city’s drinking water.
It is additionally a shallow aquifer, with parts of it only five feet beneath the ground.
Gary Schimek, natural resources manager for Redmond, said his staff recommended the regulations based on culminating factors.
These include the shallow aquifer, its location beneath the downtown urban center and the lack of a protective layer of sediment.
Their main concern is a lack of scientific data showing reclaimed water, once it entered the Redmond aquifer, would be safe to drink.
“We are very supportive of the use of reclaimed water for beneficial uses outside of our critical aquifer recharge area,” Schimek said.
Reclaimed water is already being used outside of the recharge area by the Willows Run Golf Course and the city’s 60-Acre Park.
The recharge area is relatively unique in the county and potentially the state, Schimek said.
The aquifer’s lack of a protective layer of sediment means water may pass more easily through it without being naturally cleaned.
Reclaimed water has higher nitrate levels than drinking water and Schimek wasn’t aware of studies showing if it would be filtered out before reaching the aquifer.
“We’re kind of using a precautionary principal here,” he said.
The level of water in Redmond’s aquifer fluctuates with the seasons, getting lower in the summer and recharging during the rainy season.
King County has reached near drought conditions in 2015 following a dry summer.
According to DOE, at least one municipality in Thurston County is using reclaimed water to refill its aquifers.
The City of Othello is also looking into using reclaimed water to recharge its Odessa aquifer, which is being depleted.
If studies emerge showing reclaimed water is safe to use in Redmond’s aquifer recharge area, Schimek said they may re-examine the prohibition on its use.
Other protections for the aquifer are in place, including encouraging businesses to limit runoff, which can make its way into groundwater supplies.
The aquifer stretches in an L shape from north of Sammamish, west through Redmond and to south of Woodinville.