Faced with the presence of low levels of toxic perfluorochemicals in one of its wells, the Issaquah City Council voted unanimously Monday night to spend $150,000 to lease a device that could clean the well’s output of drinking water.

Unregulated perfluoroctane sulfate, known casually as PFOS, has been detected by testing conducted on Well 4 since 2013, through the city’s participation in a voluntary program of the Environmental Protection Agency. City water meets the EPA’s non-binding safety standard for levels of PFOS, but a January New York Times Magazine article called out Issaquah’s and other cities’ perfluorochemical levels as exceeding stricter standards proposed by university researchers.

Well 4 is housed alongside Well 5 of Northwest Gilman Boulevard; both have been temporarily shut down as of early March pending chemical composition testing of the water and the enactment of a cleaning plan. But with summer peak use arriving in a matter of months, a Public Works Operations director told the council Monday that the city had a limited amount of time to begin sanitizing the water.

“While we’re looking at our short-term options, one of the things we want to avoid is drawing PFOS down into Well 5,” Emergency Management Director Bret Heath told the council Monday. “We believe we have a window here in which we can accomplish that.”

Heath reported that Public Works Operations had zeroed in on a temporary treatment plant that will scrub Well 4’s water of PFOS.

The plant works by running contaminated water through two tanks of granulated activated carbon, Heath said.

The initial $150,000 will only cover one month of a lease and a security deposit on the system. Long-term costs have yet to be calculated for a council vote. But with only three ready-to-install plants in the country, the city needed to act as soon as possible, Heath said.

“There are other water utilities looking for this,” he said.

Heath reported the ongoing cost of the plant at approximately a $6,000-per-month lease and $60,000 every two to six months to replace the carbon in the tanks.

Councilmember Tola Marts estimated that could place the plant’s annual cost between $180,000 and $360,000 annually.

“This is a short-term, temporary solution until we can implement a longer term solution which we’ll be talking about April 1,” Heath said.