Improvements begin at McDowell Grove Forest Preserve near Naperville

Work has begun to improve McDowell Grove Forest Preserve while creating flood-control features along the West Branch of the DuPage River.

Crews have started the process of selectively removing buckthorn, honeysuckle and other invasive and aggressive plants along 33 acres of floodplain in the Naperville-area preserve. The work is being overseen by the DuPage County Forest Preserve District and DuPage County's stormwater management department.

Nonnative plants, such as buckthorn, flourish in Illinois soils, crowding out and threatening native species.

“Some people may not even know the river is there,” said Nicholas Fuller, a natural resource project coordinator, as he drove Monday along a path near the West Branch. There's so many invasive plants along the path that the river is difficult to see.

Removing invasive plants will not only make it possible for trail users to enjoy a view of the river, it also will improve the flow of floodwater when the river overflows into the floodplain. Right now, brush and invasive trees are restricting the flow.

The restriction of that water through floodplain areas is one reason there's been flooding problems upstream in Warrenville, officials said.

“The water is not flowing through here quick enough,” said John “Ole” Oldenburg, director of the forest preserve's office of natural resources.

Of course, Oldenburg said, there are other contributing factors, including bridges, that are impeding the flow of river water. Officials are planning to rebuild bridges at Williams and Warrenville roads, which will help address that issue.

Warrenville is hoping to replace the Williams Road bridge.

The county is seeking funding to rebuild the Warrenville Road bridge.

In addition, DuPage's stormwater management department is creating a flood-control berm along River Road.

“Once all those are completed, there should be a marked improvement in floodwater conveyance down the river,” Oldenburg said.

In addition, there will be an improvement in the water quality and habitat of the river.

That's because removing invasive plants allows for an area to be restocked with floodplain-appropriate native plants.

The native plants will hold the soil and prevent it from washing into the river and becoming sediment.

“By summer we'll see a vibrant green foundation start to take hold that will not only offer better flood-control features for local residents but also provide more diverse habitat for native wildlife,” Oldenburg said. “It will be an area enjoyed by hikers, anglers, paddlers and birders alike.”

In addition to the work in the floodplain areas, forest preserve district officials say they also plan to restabilize eroded reaches of the riverbank with cobblestone.

That will help keep the channel intact and allow aquatic vegetation to take root, officials said.

Another part of the project calls for riffles — a place where rocks make the water flow unevenly — to be added at five locations along the river, between Diehl Road and the site of the old McDowell Grove dam. One of the riffles is being built at the location of the former dam, which was removed years ago.

Officials say the riffles will allow water to more easily flow during heavy rains. Riffles also oxygenate the water and provide niche wildlife habitat, they said.

“It gives habitat to more oxygen-loving fish species and insects,” said stream ecologist Jessi DeMartini, adding that the old dam site will be “a great fishing spot.”

Overall, Oldenburg said the goal of the project is to create sustainable banks and put habitat back into the river.

“We're trying to achieve sustainability,” he said.