What's causing alarmingly high E. coli bacteria counts in two locations discovered along the Red Run Drain in Sterling Heights is still a mystery. But where it's coming from is not.

It's from the city of Warren storm drains, Macomb County Public Workers Commissioner Candice Miller said.

"To put it in context, if you have E. coli counts of 300 (per 100 milliliters of water) or more, you're closing beaches," Miller said, at a news conference Wednesday. "And what we found at two different spots was 2,400, which is the maximum that the testing will go to. So they were off-the-charts — I'm sure they are much higher than that. That is very dangerous to human contact."

The hotspots were discovered after reports from a woman who was kayaking on the Red Run Drain in late November when she encountered a sheen on the water surface just north of 14 Mile Road and west of Schoenherr Road. The drain is a historic drainage canal that flows to the Clinton River and on to Lake St. Clair.

Macomb County Public Works crews recovered the sheen and tested it, discovering heightened levels of E. coli that they followed along the drains with further tests, Miller said. The hotspots were discovered in a 36-inch storm drain pipe at 14 Mile Road just east of Schoenherr, and another spot in a 72-inch storm drain pipe along Schoenherr just north of I-696.

The pipes belong to the city of Warren.

"We went as far as we could," Miller said. "We contacted them, we let them know what we've found here, and they have assured us they are going to be right on it."

In a statement later Wednesday, Warren Mayor Jim Fouts said he "immediately directed our city staff including the Public Service Director, the City Engineer, and the head of our wastewater treatment operations to investigate the source of these high coliform levels" upon learning of them Tuesday evening.

Drinking water in Warren is fine, City Engineer James VanHavermaat stressed.

"This is totally unrelated to drinking water," he said. "It’s a storm sewer; the drinking water supply is completely safe."

Macomb officials informed the city of their findings Tuesday afternoon, and city staff are conducting water tests in the area of the drains, VanHavermaat said.

"We don’t believe right now that there is any imminent environmental threat from a high coliform count," he said. "We don’t know yet if this is an illegal connection causing this; whether it’s the result of animals.

"It’s going to take some more investigation to find out exactly where it’s coming from."

Read more:

Saving Lake St. Clair: A Free Press special report

The discovery comes as Macomb County officials have stepped up their inspections of drains in their county, and called on upriver Oakland County to better control E. coli and other pollution reaching the Clinton River and Lake St. Clair.

Chronic E. coli contamination every summer keeps prime beaches on Lake St. Clair closed for days or weeks, and areas of algae-laden, shoreline muck for decades have fouled the experience for lakefront residents and users.

Fouts noted that coliform bacteria exist in the intestines of all warm-blooded animals.

"These high counts could be the result of wildlife in the area," he said.

Miller, however, expressed skepticism regarding potential animal culprits. The E. coli levels being found at the hotspots almost certainly rule out bird and animal feces washing off paved surfaces into drains as the source, she said. It's "almost always" human waste at these levels, she said.

"There's some sort of connection; something unusual is happening to have these high-high-high E. coli counts," she said.

Miller's department in February found a 10-unit apartment complex in Eastpointe with an illicit connection flowing raw, untreated sewage into a drain and on to Lake St. Clair — "250,000 gallons a year for more than 35 years," she said. The city fixed the problem within two days, she said.

"There are so many factors that go into what happens in Lake St. Clair," she said.

Contact Keith Matheny: 313-222-5021 or kmatheny@freepress.com. Follow on Twitter @keithmatheny.