The fall colors in Fullersburg Woods are reflected across the surface of Salt Creek.

Life moves a little more leisurely in this forest preserve in Oak Brook, and so does the creek itself. “Going with the flow” reads a trail sign at the foot of an old gristmill.

Two years ago this month, the Graue Mill dam was removed and, with it, the constant din of rushing water. Kayakers no longer have to get out of the water and go around the dam. Instead, paddlers and visitors to the millhouse-turned-museum encounter a newly revitalized stretch of Salt Creek.

“Being here and seeing the changes at Fullersburg, it’s magnificent,” said Erik Neidy, director of natural resources for the Forest Preserve District of DuPage County.

Below the surface, too, are encouraging signs. The nonprofit Midwest Biodiversity Institute this year documented eight native fish species previously found only downstream of the former dam site: hornyhead chub, emerald shiner, rosyface shiner, central stoneroller, smallmouth bass, blackside darter, logperch and northern pike.

“As a scientist, I’m always looking for physical validation that our predictions did work out,” said Stephen McCracken, director of the DuPage River Salt Creek Workgroup, a nonprofit coalition of stakeholders. “I’m extremely happy with the results.”

Why the dam was removed

During the Great Depression, President Franklin D. Roosevelt’s Civilian Conservation Corps built the dam and a boathouse that became a nature education center and still looks like a log lodge. The dam wasn’t from the same period as the 19th-century gristmill.

“But when you looked at the mill, the wheel and it together, your brain does create this pattern, right? You can see it all working together, even though it was really a fiction,” McCracken said.

The dam was also associated with a serious decline in fish and insect biodiversity, aquatic habitat and water quality parameters such as dissolved oxygen, McCracken said.

“Essentially, you’re creating a lake on a river system,” he said. “And you do that by putting the barrier in place so it essentially floods that area up.”

Such “impoundments” trap sediment along with decaying leaves, dead plants, fish and bacteria, and as those materials decompose, they use up a lot of dissolved oxygen in the water, the forest preserve district said ahead of the project.

Still, many Oak Brook residents were attached to the Graue Mill dam — a backdrop to family photos — and objected to its removal.

“We’ve had people directly say to us, ‘I didn’t like it, but now I get it,’ and I think because we did what we said we were going to do,” Neidy said. “We didn’t remove the mill. We actually improved the mill. And now the wheel turns, and there’s better water quality in the little raceway.”

‘Build it, they will come’

The project was the result of a partnership between the forest preserve district and the DuPage River Salt Creek Workgroup. The funds for the roughly $9.5 million cost were raised from local wastewater treatment entities, including the Metropolitan Water Reclamation District of Greater Chicago.

The dam removal was part of a broader effort to restore about a mile and a quarter of Salt Creek. Crews, for instance, enhanced riffles — faster, shallower areas that support communities of fish and bugs — with boulders and rock. A new stone overlook faces the dam-free creek.

“So when you’re walking along the stream, it looks better, it sounds better, it smells better,” Neidy said.

As part of upland restoration work in Fullersburg Woods, invasive buckthorn and honeysuckle were cleared, returning sunlight to the forest floor.

“We had great spring ephemerals. All the early spring wildflowers came up this year really well, and then we’re seeing even more species come up throughout the year,” Neidy said. “So that’s one of those, almost if you build it, they will come type of thing.”

Restoration efforts continued this year with native plantings — the addition of 50,000 plugs. Some are pollinator-friendly. With deep roots, prairie cordgrass helps stabilize banks of the creek. Another 15,000 plugs will be put in next May.

“We have rose mallow, which is a gorgeous pink flower that grows in mud flats,” Neidy said. “We have royal catchfly, which is bright red. It’s actually more conservative, more rare. There’s a bunch of those coming in.”

Monitoring will continue

Pre-project, 16 native fish species in the Salt Creek basin were found only downstream of the dam, based on surveys run over 20 years. Eight of these have now moved upstream, McCracken noted, and further monitoring will reveal any changes in their and the remaining eight’s distribution (none of the remaining eight species were present anywhere in the basin in 2025).

“You need a couple of years’ sampling to see how that all works out,” he said. “But the eight that I was most confident in that they should really be upstream under better conditions — in other words, if the barrier was not there — have all made the jump.”

Officials hope to find smaller, nongame fish, certain types of darters, because “they’re excellent host species” for mussels and other aquatic organisms, Neidy added. “And they’re an indicator of good health and good biodiversity, because they need cleaner water.”

For McCracken, one of the more unexpected outcomes of the project has nothing to do with technical data. Over the summer, he observed, where the old dam was, a bunch of kids fishing off the boulders.

“It’s been very gratifying,” he said, “to see how positive people are to the river in its current state.”

https://www.dailyherald.com/20251108/news/its-magnificent-how-a-dam-free-salt-creek-fullersburg-woods-have-been-revitalized/