Places across St. Charles County where you can see healthy watersheds at work.
Some of these places store floodwater, clean runoff and give wildlife room to live. Others show stormwater work built into parks, streets and neighborhoods. Pick a goal to filter the map and the list.
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Pins marked “approximate” show the general area. Use each place’s Directions link for the exact location. Map data © OpenStreetMap contributors.
West Alton
The 1,121-acre park sits where the Missouri River meets the Mississippi. It floods often, so the state is letting much of it return to natural floodplain instead of fighting the water.
What to look for: Where the two rivers meet, the water color changes, the restored wetland and bottomland, and the signs that explain both rivers.
Photo: Kbh3rd, CC BY-SA 3.0, via Wikimedia Commons
West Alton
About 3,700 acres of Mississippi River floodplain, with roughly 1,200 acres of restored marsh and bottomland prairie. The Army Corps of Engineers manages the sanctuary, and the Audubon Center explains how the river, the birds and the floodplain fit together.
What to look for: Swans and eagles in winter, the restored marsh, and the river and flyway exhibits at the Audubon Center (free; check its hours before you go).
Photo: Andy Reago & Chrissy McClarren, CC BY 2.0, via Wikimedia Commons
Portage des Sioux area
A 918-acre wetland in an old Missouri River oxbow. It is a remnant of the marsh that once stretched across the lowlands from St. Charles toward Alton. A wetland like this soaks up floodwater and filters it slowly.
What to look for: The shallow marsh pools, waterbirds during spring and fall migration, and how flat and low the old riverbed is.
Weldon Spring area
6,987 acres of oak woodland, restored prairie, seasonal wetlands and more than 30 fishing lakes, all inside a fast-growing part of the County. It is part of an Important Bird Area that also takes in Weldon Spring and Howell Island.
What to look for: The restored prairies, the wetland edges, the lake shorelines, and the MDC programs held on site. Check MDC for any closed areas before you go.
Weldon Spring area
8,398 acres of forest, bluffs and Missouri River bottomland. The Katy Trail runs right through it, connecting this natural area to towns up and down the river.
What to look for: The bluff-top views over the river bottoms, the forested hollows, and how the trail follows the floodplain edge.
Photo: Yinan Chen, Public domain, via Wikimedia Commons
Missouri River, near Chesterfield
A 2,548-acre island in the Missouri River. The whole island went under water in the 1993 flood, and its bottomland forest and wetlands are built to take high water.
What to look for: Bottomland forest and side channels. You can only reach the island by boat, so many visitors view it from the riverbank.
Riverside Landing, St. Charles
Dardenne Creek drains about 165 square miles of the County. In 2010, after clean-up work, a 6-mile stretch was taken off the state’s impaired-waters list. The Blueway was Missouri’s first water trail of its kind, and the County is extending it upstream toward Bluebird Meadow Park in Dardenne Prairie.
What to look for: Paddle from Riverside Landing, where Dardenne Creek meets the Mississippi. Watch the creek banks, the riffles and the wildlife along the water. The park offers kayak rentals.
Wentzville, Lake Saint Louis, O’Fallon
A fast-growing watershed that feeds Lake Saint Louis. It now has a nine-element watershed plan prepared with Missouri DNR (2025 draft), which lays out where runoff and sediment come from and what local projects could fix it.
What to look for: Read the plan first, then look at how new neighborhoods, creeks and the lake connect along the Peruque Creek corridor.
500 S. Riverside Dr., St. Charles
A 16-acre riverfront park beside Historic Main Street, with direct access to the Katy Trail. It sits in the Missouri River floodplain: when the river reaches about 31 feet at the St. Charles gauge, the trail through the park can close.
What to look for: How low the park and trail sit beside the river, and the big trees along the bank. Check the river level before you go.
S. Fifth St. at I-70, St. Charles
A large mixed-use district of shops, offices, hotels and homes that built green infrastructure into the development. It shows that stormwater practices can fit into a busy, walkable commercial district.
What to look for: The planted areas along the streets and walkways, and where runoff from the pavement and roofs goes.
St. Charles
A walkable neighborhood built around a network of lakes and canals that hold and slow the runoff from more than 700 acres. Its stormwater system is also its main scenery.
What to look for: How the canals and lakes run alongside the streets and homes, and where the runoff flows in from the streets.
Photo: Wikimedia Commons contributor, see file page, via Wikimedia Commons
Wentzville
A city park built around stormwater-smart design: bioswales, rain gardens, native plantings, and a sediment forebay that keeps soil out of the lake. Wentzville Parks manages it with MDC.
What to look for: The signs at the sediment forebay at the east end of the lake, and the bioswales and rain gardens. The boardwalk has been closed for safety, so check with the city before you go.
Wentzville
An ordinary detention basin turned into a planted one, with more than 500 native plants that slow, soak up and clean runoff from the site. It shows how an existing basin can be upgraded instead of rebuilt.
What to look for: The native plantings across the basin floor and how the water moves through them. The city has a video tour on its project page.
260 Brown Road, St. Peters
The University of Missouri’s County office. It runs the Extension Master Gardener course and hands-on workshops, offers soil testing, and has specialists in horticulture, Missouri Master Naturalist and community leadership. It also runs 4-H and nutrition and health programs. Call 636-970-3000.
What to look for: The Master Gardener Demonstration Garden on site. A soil test before you fertilize is also an easy way to keep extra nutrients out of runoff.
Each tour groups nearby places so you can see several in one trip. Click a stop to find it on the map.
Start on the St. Charles riverfront, then head to West Alton and Portage des Sioux, where the big rivers spread out.
A day of forest, prairie and river bottom on the County’s south side, plus a paddle on Dardenne Creek another day.
Neighborhood-scale stormwater work you can walk right up to.
These sites are owned and managed by the agencies and cities listed. Including a site here doesn’t imply a partnership or endorsement. Check each site’s own page for hours, closures and rules before you go.
