U.S. Air Force officials Tuesday disclosed a 150,000-gallon spill of wastewater laced with invisible toxic perfluorinated chemicals, discharged at least six days ago from a tank at Peterson Air Force Base, into the Colorado Springs sewer system.

The spill, which Air Force officials said they’re investigating, happened as the Air Force increasingly faces scrutiny as a source of groundwater contamination nationwide.

The surge of waste containing elevated perfluorinated chemicals (PFCs) — used at military airfields to douse fuel fires and linked by federal authorities to kidney cancer, testicular cancer, low birth weights and other health problems — flowed through a Colorado Springs Utilities wastewater treatment plant before crews could try to block it. Then it trickled into Fountain Creek.

“Even if we would have been able to head it off at the plant, we’re not equipped. I don’t know of any wastewater plants in the country equipped to remove PFCs,” utilities spokesman Steve Berry said. “We would not have been able to remove that chemical before it was discharged back into the environment from our effluent.”

Fountain Creek flows south toward Pueblo and into the Arkansas River.

Pueblo Board of Water Works spokesman Paul Fanning said Pueblo didn’t hear about the spill until reporters made inquiries Tuesday.

“We don’t use any groundwater or surface water from Fountain Creek. We use water from the Arkansas River taken upstream from where Fountain Creek flows in,” Fanning said. “But it is not a good thing to have those contaminants anywhere in our water. There are some reported health effects. It is in our interest to protect our public.”

Air Force officials couldn’t be reached to discuss the spill.

“We take all environmental concerns seriously and have opened an investigation to determine the cause of the discharge and prevent it from happening again,” Col. Doug Schiess, commander of the 21st Space Wing at Peterson AFB, said in a prepared statement.

The PFC-laced waste was held in a tank at a firefighter training area on the base, located at the southeastern edge of Colorado Springs. PFCs are a component in the aqueous film-forming foam used to extinguish fuel fires.

Air Force officials said in the statement that they discovered the spill Oct. 12 during an inspection. They notified Colorado Springs Utilities the next day. The tank was part of a system used to recirculate water to a firefighter training area.

PFCs at levels exceeding a federal health advisory limit already had contaminated groundwater and public drinking water systems south of Colorado Springs, an area that is home to an estimated 80,000 people. Peterson AFB is suspected as one source. Federal Army Corps of Engineer officials conducted an initial investigation.

Air Force officials have said the military’s past use of PFCs for firefighting was legal, but that crews are discontinuing their use except in emergencies. PFCs are not regulated under federal law. Air Force civil engineers are in the process of assessing PFC contamination around the country. They say they’ll put out a report in the spring.

The PFC-tainted area south of Colorado Springs ranks among the hardest-hit of at least 63 areas nationwide where PFCs have been measured in public water systems at levels the Environmental Protection Agency deems dangerous.

In Colorado, government well test data show PFCs have contaminated groundwater throughout the Fountain Creek watershed, nearly as far south as Pueblo, at levels up to 20 times higher than that EPA health advisory limit of 70 parts per trillion.

Public-water authorities in Fountain, Security and Widefield have scrambled to provide enough alternative water. Security has been purchasing millions of gallons of diverted Arkansas River water from Colorado Springs, installing new pipelines and minimizing pumping from contaminated municipal wells. Since Sept. 9, Security has not pumped any water from wells, water and sanitation district manager Roy Heald said. “This spill does not affect us immediately,” Heald said. “Our only concern would be the long-term effect on Fountain Creek and the Widefield Aquifer.”

Some parents south of Colorado Springs began paying for bottled water — to be safe. A contractor delivers emergency bottled water to at least 77 households.

The Air Force has contributed $4.3 million to help communities deal with the contamination.

Colorado Springs utilities crews will work with the military “to keep PFCs out of our system. That is the goal,” Berry said. “How do we protect our customers and our system from this chemical? That is the focus. It goes beyond the Air Force. It is any industrial process that may use that chemical.”

El Paso County Public Health “takes this discharge seriously and will coordinate with the Colorado Department of Public Health and the Environment to collect water samples along Fountain Creek, if warranted,” spokeswoman Danielle Oller said.

CDPHE has been informed, agency spokesman Mark Salley said, adding: “It is under investigation by the Air Force, and the department is waiting for information. … The Air Force has demonstrated its commitment to identifying and addressing PFC contamination at Peterson Air Force Base and facilities nationwide.”