CROWN POINT | Federal authorities are investigating the Lake County Health Department, probing allegations that employees there were falsifying drinking water tests, county officials confirmed Tuesday.

While officials have not identified any threat to public health, the U.S. Environmental Protection Agency is investigating the extent of the potentially affected testing.

The EPA is examining the scope of allegedly false reports filed by two Health Department employees who have since been fired, county officials said.

"We thought there were issues with the lab work," Assistant County Attorney Joe Irak said. "We notified the agencies involved."

Randy Ashe, special agent in charge of the EPA's Criminal Investigation Division's Chicago office, said Tuesday he could not "confirm or deny anything regarding Lake County. In general, in any situation, if we have any information that there is a health safety issue, we immediately refer it to the proper place."

The Lake County Health Department used to test water for various customers, including private drinking water supplies and community pools. It also occasionally tested public waterways.

The department shuttered its lab in late February, citing a lack of funds to upgrade the lab and its equipment to meet state standards. But according to Lake County Attorney John Dull, concerns over the lab reports also prompted the decision to close.

"I don't think the (outdated) equipment was the problem," he said.

Amy Hartsock, spokeswoman for the Indiana Department of Environmental Management, said the agency's Drinking Water Branch had worked with county officials since at least February regarding the allegations.

"We were made aware of issues concerning quality assurance and quality control at their lab," Hartsock said. She said IDEM helped determine which water systems were using Lake County for testing so those groups could notified and aided in finding alternative labs.

IDEM alerted a group of small businesses with groundwater systems that used Lake County to test water for bacteria and nitrates. Hartsock said in February the agency told the small businesses -- where the water in question likely circulated through drinking fountains -- that the companies needed to switch labs.

Hartsock said Tuesday she did not know the locations of the businesses or how many IDEM notified. But she called the number "small."

"We can't guarantee that there might not have been something inaccurate (in their tests)," Hartsock said. "We cannot go back and sample the samples that might have been questionable."

She said she could not comment on any ongoing investigation the EPA was handling.

Federal and local authorities could not confirm exactly which water tests -- or how many -- were compromised. They also said they could offer no estimate of how long the alleged violations may have taken place.

County officials said they could not comment further because federal authorities have asked them not to discuss the situation.

Dull said the county did not want to stop providing testing services to residents and has since outsourced its water testing to Microbac Laboratories in Merrillville.