LEXINGTON — The ParkLands Foundation’s Sweeney Woods preserve is a work in progress, but that work is showing results.

By taking the regularly flooded 40 acres of bottomland out of agriculture production and planting trees instead, the preserve is preventing tons of sediment and topsoil from entering the Mackinaw River, which flows through the northern edge of the preserve with about two miles of river frontage, said land steward Jason Shoemaker.

The 115-acre preserve is located on both sides of the river, but the 77 acres on the south side are more accessible and contain the hiking trails.

“We’ve had a lot of spring ephemerals, woodland phlox, trillium other native flowers and understory, so it’s healthier timber now,” said Shoemaker.

The preserve is 1½ miles north of Lake Bloomington with a parking lot off North 1725 East Road, just south of the Mackinaw River.

From the parking lot, you can carry (or drag) your canoe or kayak about the equivalent of a long city block to the river to launch your boat. The condition of the launch area depends on river levels. Expect it to be muddy, but at least there are no high banks and it is one of the few areas along the river with good parking for paddlers.

The preserve has about 2½ miles of trails. During my late afternoon hike last week, I was grateful the trail had been recently mowed, but also grateful I had brought bug repellent to fend off possible ticks and mosquitoes.

A couple of 12-spotted dragonflies patrolled the trail. A pair of monarch butterflies flitted by. Based on the number of milkweed plants emerging, I expect to see many more butterflies later in the season.

At least the trees can’t run or fly away. My favorite — practically everyone’s favorite who visits here — is a centuries-old bur oak that towers over the preserve along the trail in the uplands.

Shoemaker said there is no way to know for sure how old the tree is without a core sample but noted, “It was big when I was a kid,” and could be a few hundred years old.

Much of the work is done by volunteers from the foundation, Master Naturalists and other groups, as well as volunteer land steward Tom Farmer; AmeriCorps teams; and interns, such as Steven Burkett of St. Louis, a junior in environmental studies at Illinois Wesleyan University, and Allyse Barnowski of Round Lake, a senior in environmental system science and sustainability at Illinois State University.

ParkLands began restoration work in 2010.

“It’s turned into a real nice restoration area,” said Shoemaker.