ALPENA, Mich. — A combat center in northern Michigan has become the third military base in the state to test positive for contaminated groundwater.

Preliminary results came in this week for tests conducted at five locations at the Alpena Combat Readiness Training Center earlier this year, said Capt. Brian Blumline, a civil engineer for the base. Blumline said all the sites showed elevated levels of perfluorooctanoic acid and perfluorooctyl sulfonate, which are contaminants from firefighting foam that was used in training at the base many years ago. They were considered safe at the time.

Contaminants seeped into the groundwater when the foam was used, and there’s concern a plume could have traveled over time and entered residents’ well-water sources.

“It’s been in our groundwater for a long time and the test numbers came in very high,” Blumline said.

The maximum level of such contaminants deemed safe in Michigan is 70 parts per trillion, which Blumline described as one drop of dye in three Olympic-sized swimming pools. State Rep. Sue Allor said the test results at the base were at or about 80,000 parts per trillion.

“My feeling right now is there needs to be more action and this isn’t moving fast enough,” Allor said. “We’re talking about people’s lives here. I want to make sure the health, safety and welfare of residents, animals and property are the top priority in this.”

Blumline urged the public to attend an informational meeting at the base next week. He said state environmental and health agencies will provide updates on what steps will be taken moving forward.

“We’re not going to be able to fight this without community support,” he said.

Contamination also has been found at Camp Grayling and the former Wurtsmith Air Force Base.

The Alpena base is expected to receive more definitive test results in January.