Before he died in 2009, legendary Au Sable River angler Rusty Gates often said he didn’t much care to travel south of M-55, because, with some notable exceptions on Michigan’s west side, M-55 serves as an unofficial trout border. The road cuts across the middle of lower Michigan’s mitten. Above it you’ll find the birthplace of Trout Unlimited, a national organization dedicated to the conservation of freshwater habitats for trout and salmon. Below it you’ll find most of the state’s economy, noise, and traffic.

In Dexter’s Mill Creek, you’ll also find brown trout. Mill Creek is more than two hours south of M-55. Summer creeks in these parts can run as tepid as a half-swallowed cup of coffee and hold few fish worth pursuing.

Once upon a time, that was Mill Creek’s destiny. Until the leaders of Ann Arbor’s Trout Unlimited chapter had a hunch. Even better, they had expert fisheries scientists. And they had the teenaged boys of Dexter—drawn to the nearest flowing water like Huck Finn’s descendants, they would eventually unlock the creek’s fishing secrets.

For decades, the more than 600 members of AATU had the same conundrum as some other chapters across America—lots of passion, no local trout water. Members met in church basements and traveled hours north to do habitat work on someone else’s home water.

In the late 1960s, an aspiring special education teacher named Bill Phillips aimed to join AATU on an Au Sable River weekend. When his car broke down, he hitchhiked the 190 miles north.

“I was just starting out in fly fishing so I spent a lot of time watching,” Phillips recalls. “There was this one guy. It was just incredible what he could do with a fly rod.”

That guy was Tom Edsall, a fisheries biologist who would become chief scientist at the U.S. Geological Survey office in Ann Arbor, work there forty years, and lead its Great Lakes fisheries research. Edsall, who died last year, ended up giving Phillips a ride back to Ann Arbor. Years later, they became partners in the creation of a Mill Creek trout fishery.

Before it flows through Dexter, much of the 142-square-mile Mill Creek watershed drains a breadbasket of potato, corn, dairy, soybean, wheat, and hay farms. The farmers used underground tiles to dry their swampy lands, with Mill Creek as the drain.

Over time, stewards of the Huron River envisioned a new kind of Mill Creek. They wanted to remove an old dam in downtown Dexter, drain the millpond, and reestablish a free-flowing stream. At the same time, Ann Arbor TU started searching for local trout water.

“It was a case of right place, right time,” says former AATU president Mike Mouradian. Creating a new trout stream would take science. “And when you’re in a town like Ann Arbor, you can throw a rock and hit a dozen PhDs.”

The founding fathers of the Mill Creek trout project were Edsall and Carlos Fetterolf, a former president of the American Fisheries Society, who also has since died. Phillips led the boots on the ground.

They started their quest in 2006, placing temperature monitors in the Huron River. Initial results were disappointing. The dog days of summer pushed water temperatures past lethal levels for trout. But a lone monitor in Mill Creek, downstream of the millpond, showed average midsummer temperatures below ­seventy—potential trout water.

In 2008, the Dexter millpond came out. The stream flowed freely and cooled a bit more. In 2009, AATU went back to work and found plenty more creek water below 70 degrees upstream. It seemed the creek’s naturally cool headwaters were further chilled by groundwater sent by farmers’ drain tiles. Edsall called it “a manmade cold-­water creek.”

Armed with the temperature data, AATU earned approval from the Michigan Department of Natural Resources to stock the first 2,000 brown trout in the creek’s coolest stretches in 2011. They moved downstream and stocked 5,400 more over the next two years. Surveys showed the fish thrived through hot summers and cold winters.

“Then reality hit,” recalls Phillips. “These fish weren’t that easy to catch.”

In summer 2013, Phillips worked a booth at a Dexter festival to promote the creek. The village council president, Shawn Keogh, stopped to say thanks then chortled when told the trout eluded Trout Unlimited members.

“You guys need to talk to my neighbor’s kid,” Keogh told Phillips. “He’s catching trout in the creek.”

Unbeknownst to AATU, Jake Taylor, then fourteen, was on the prowl for all kinds of fish in Mill Creek. Phillips went on the prowl for Jake. Soon Phillips had photos showing the teen holding football-shaped brown trout tempted by Mepps spinners, hot dogs, and corn kernels.

Those techniques sparked minor controversy among fly fishing purists. No matter, Phillips reasoned, and prodded Jake to write a photo-filled Mill Creek fishing guidebook to inspire more anglers to try.

That same summer of 2013, another Dexter kid, Ethan Cramer, heard the Mill Creek rumors. A Michigan State University student, Cramer has never been to a Spartan football game because his fall Saturdays are reserved for fly fishing. Cramer caught his first Mill Creek trout on a fly rod moments after stepping into the creek.

“It was just unbelievable to catch a trout two minutes from my back door,” Cramer says. “It was the best present I could imagine. Now I have a sense of escape right in my backyard.”

Following on Jake Taylor’s work, Cramer wrote his own Mill Creek fly fishing guide. Taylor and Cramer donated their guidebooks to AATU.

Meanwhile, Phillips launched a “Mill Creek Reporters Club” and documented fish of more than eighteen inches coming to net. Cramer and others have caught brown trout over twenty inches.

Building on AATU’s success and inspired in part by the growing fishing reports, the Michigan DNR will keep stocking 2,220 trout in Mill Creek annually through next year. AATU members will stock 500 more. They’re currently negotiating the next phase of their study with the DNR.

Mouradian says they’re still getting reports of 20″ trout—”probably from our original planting”—that have survived thanks to TU’s “catch and release” policy. More important, he says, small fish planted three to five years ago are now hefty 15-inchers, proving that trout can flourish long-term.

And they’re not just flourishing in Mill Creek. “When it gets warm and shallow, they go find oxygen and cooler water,” says Phillips. “They’ve been caught [in the Huron River] from Hudson Mills all the way down to Delhi Rapids.” When the weather turns cool again, “they come back and spawn in Mill Creek.”

TU aims to protect trout streams and restore degraded trout water. Yet brown trout are not native to the United States. In that respect, every brown trout river in America is manmade. Mill Creek is more manmade than most.

“We’re dancing right on the edge of what we’re supposed to do as a TU chapter,” says Mouradian. “But you’ve got to work with what you have.”

Cramer is a bit more mercenary.

“There used to be a lot more trout streams in Michigan and around the country,” he says. “So, when we have the opportunity to actually create a trout fishery from scratch, I think Trout Unlimited should be really excited. It’s tough to get people interested if there’s no fishing nearby.”

A version of this article previously appeared in Trout Magazine.