Luke Ackerman is a persistent guy, but after four years of making 311 calls, he gave up trying to tell Baltimore City about fecal odors coming from a former mill race that flowed into the Jones Falls.

As far back as 2007, he said, the stench was noticeable as he crossed the Union Avenue bridge over the Jones Falls, especially in mid-summer and the dead of winter when the river’s water level was low.

“I would walk past the spot every day to get to the Light Rail station to go to work. And pretty routinely, a stink was coming from the mill race at the river,” he said.

Thus began a routine in which the then-28-year-old said he would report the foul smells to the city’s 311 number for non-emergency city issues.

“At first I would call about twice a month,” he said. “When nothing happened, I went online and started checking my Service Request numbers. I saw a bunch of them were marked ‘nothing found’ or ‘NA.’ Sometimes, my SRs had been closed within hours of my call. That made we wonder if the city even bothered to send out an inspector.”

“I got less and less motivated to call them,” Ackerman said. “But I persisted – even submitting video and photos on occasion – until 2011 when I changed my commute route.”

What Ackerman had been reporting a decade ago the Department of Public Works announced as a fresh discovery last week – the steady flow of sewage coming into the Jones Falls by means of an unmapped private pipe that was intentionally sawed off inside a city storm drain tunnel.

During what was described as routine monitoring, DPW analysts had tested the water near the Union Avenue bridge last month and found high levels of ammonia, which is associated with sewage.

The analysts traced the source of the sewage some 1,500 feet up the hillside to a tunnel that ran into a one-time cotton mill that’s now leased to artists, light industry and a CrossFit center.

The property, at 3500 Parkdale Avenue, is owned and managed by the Kenneth Mumaw family, which operated a nearby plumbing company. (The elder Mumaw worked at the former Hooperwood Cotton Mills, which was sold to the family in 1988, according to property records.)

The management firm has not commented on the leak, while DPW officials say it is too early to tell how and when the sewer pipe got inside a public storm drain tunnel.

Sewer pipes are supposed to be separate and apart from storm water drains, so that sewage does not mix with rainwater and flow into local waterways.

A combined sewer-drain line is against city policy and violates the terms of the pollution consent decree that Baltimore entered with the Maryland Department of the Environment (MDE) and the Environmental Protection Agency back in 2002.

The decree is now before a federal judge, who is reviewing the terms of an extension of the decree – aimed at finally ending routine sewage overflows into the Jones Falls and Inner Harbor during heavy rainstorms.

DPW said yesterday that “it remains unclear how the 100-year-old sewer line ended up being placed in the 82-year-old storm drain.”

Adding to the mystery: “Why and when the sewer main was cut also is not known,” said the agency in a press release, which noted that “modern PVC connections are adjacent [to the severed pipe] and probably date back to the early 2000s.”

So far, the evidence suggests that untreated sewage – amounting to about 7,200 gallons a day, according to DPW – has been running into the Jones Falls since at least “the early 2000s.”

As it happened, DPW had installed new sewage pipes near the old storm drain tunnel. This enabled city contractors to make a temporary fix over the weekend – pumping the sewage out of the broken line into a proper sewage main running beneath Clipper Park Road.

For now, pumping and diverting will be the solution to the sewage, says DPW spokesman Jeffrey Raymond. Over the long term, the city plans to remove the sewage pipe from the storm drain.

Raymond indicated that his office was unaware of 311 calls about sewage smells going back to 2007, but he did not dispute that such calls may have been made. (Ackerman says he saved many of his 311 calls, but a subsequent hack of his computer destroyed the file.)

In 2013, The Brew wrote about episodes of “sickly orange-brown” liquid, sometimes interspersed with milky-white liquid, under the Union Avenue bridge. A reader had taken pictures of the outflow, which seemed to be coming from a concrete pipe directed toward the former Union Cotton Mill, which was undergoing restoration as an apartment complex.

“The effluent was going strong at 8:20 a.m. and I took a photo. And it was still the same when I returned at 5 p.m. that day,” the reader told us.

A DPW official later said that the discoloration was unlikely to have been caused by sewage because there were no spikes in ammonia levels recorded at a monitoring station along the Jones Falls.