The Wetlands That Keep the Lower Ohio River Wild
Why floodplain forests, oxbows, sloughs, marshes, and seasonal high water still matter for wildlife across Southwestern Indiana, Southern Illinois, and Western Kentucky.
Hero: Hovey Lake Fish & Wildlife Area, Indiana. Image source: Indiana Department of Natural Resources.
The Lower Ohio River is more than the water between its banks. Across the Tri-State, the river is tied to oxbow lakes, sloughs, marshes, tributary bottoms, and floodplain forests that fill, drain, and change as water levels rise and fall. Those connections create feeding areas, nursery habitat, migration stops, cover, and corridors for fish and wildlife.
The problem is not simply that wetlands have been lost. Many remaining wetlands and floodplain forests no longer connect to rivers as often, for as long, or in the same way they once did. Drainage, levees, channel changes, agriculture, roads, towns, and other infrastructure have made parts of the floodplain safer and more productive for people. They have also changed how water, sediment, nutrients, fish, and wildlife move through the system.
That makes connectivity one of the most useful ways to understand wetland conservation in this region. Protecting an isolated patch of wet ground matters. Protecting or restoring the ecological processes that connect water, forest, and floodplain can matter even more.
Article contents
- The river does not stop at the bank
- What counts as a floodplain wetland?
- A region built by rivers
- Flooding is a process, not automatically a problem
- What wildlife gets from floodplain wetlands
- Four places that show the system
- How we changed the floodplain
- Connectivity is the real issue
- What restoration can actually mean
- The hard management questions
- What this means for the Tri-State
- FAQ
- References
The river does not stop at the bank
Stand beside the Ohio at ordinary water level and the river looks easy to define: water here, land there. High water makes that boundary much less convincing.
When the Ohio, Wabash, Patoka, Green, and smaller tributaries rise, water can push into low forests, old channels, shallow depressions, marshes, and backwaters. Some areas flood every year. Others connect only during larger events. Still others have been cut off by levees, roads, drainage systems, or changes to the river itself.
That movement matters because a floodplain is not just extra space for water. It is habitat. Water entering the floodplain can carry sediment and nutrients, create shallow feeding areas, open temporary habitat for fish, refill wetlands, and change which plants can survive. When water retreats, it leaves behind a different set of conditions than existed before the flood.
The U.S. Environmental Protection Agency’s scientific review of wetland connectivity describes riparian and floodplain wetlands as part of a gradient rather than a simple connected-or-disconnected category. Some are linked to rivers frequently, some seasonally, and some only during uncommon high-water events. Even wetlands that flood infrequently can influence sediment storage, nutrients, flood peaks, stream temperature, food webs, and fish habitat.[6]
If we judge river habitat only by what lies inside the normal channel, we miss much of the system. In the Lower Ohio region, some of the most valuable habitat is beside the river, behind it, or temporarily connected to it.
What counts as a floodplain wetland?
Wetland terminology can get messy fast. A slough is not exactly the same thing as an oxbow. A flooded forest is not the same habitat as an emergent marsh. A backwater may remain connected to a river, connect only at certain stages, or become isolated as water falls.
For this article, the useful question is not whether every feature fits one neat label. It is whether the habitat is shaped by water associated with the river and its floodplain.
Oxbow lake
A former river bend that has been separated from the main channel. Some oxbows retain permanent water; others become shallow or seasonally connected. Hovey Lake is a regional example.
Slough
A low, wet depression or old channel that may hold standing or slow-moving water. In western Kentucky, the name is literal enough that an entire wildlife management area is called Sloughs WMA.
Bottomland hardwood forest
Forest growing on low floodplain soils where periodic inundation and poor drainage strongly influence which trees, shrubs, and ground-layer plants can persist.
Backwater
Low-velocity water beside or behind the main current, often in side channels, old channels, tributary mouths, or floodplain depressions. These quieter waters can be very different from the main river.
Emergent marsh
Shallow wetland dominated by non-woody vegetation adapted to saturated soils or standing water. Water depth and duration can change substantially through the year.
Moist-soil habitat
Shallow wetland habitat managed to encourage annual plants that produce seeds and invertebrate-rich feeding areas, especially for migrating and wintering waterfowl and shorebirds.
The labels help us describe what we see. Hydrology explains why it behaves the way it does.
A region built by rivers
Southwestern Indiana, western Kentucky, and southern Illinois sit where several major river systems meet. The U.S. Geological Survey’s Interior River Lowland ecoregion includes the confluence areas of the Ohio, Wabash, Mississippi, Missouri, and Illinois rivers and their tributaries. The ecoregion covers much of southern and western Illinois, southwestern Indiana, and part of northwestern Kentucky.[5]
That geography helps explain why the Tri-State contains such a strange mix of habitats within a relatively short drive: farmed bottoms, cypress sloughs, oxbow lakes, broad hardwood floodplains, old channels, river islands, marshes, and heavily engineered riverfronts.
It also explains why land and water management cannot be separated cleanly here. A levee built for one purpose changes where high water can go. Drainage that makes a field usable changes how long water remains on the floodplain. Reforesting a frequently flooded field changes habitat structure for decades. A culvert, road crossing, gate, or berm can become a small piece of a much larger connectivity problem.
Regional context: USGS mapping of the West Franklin quadrangle near Evansville, Mount Vernon, and Henderson describes broad marshes and thick forests historically occupying parts of the Wabash and Ohio River floodplains. The report also documents later drainage, channelization, forest clearing, and river engineering in the area.[8]
Flooding is a process, not automatically a problem
Ask someone who lives near the Ohio River what flooding means and you may hear about closed roads, ruined crops, damaged homes, lost access, or a long week of watching the river gauge. Those concerns are real. Floodwater becomes a serious human problem when it reaches places where people, infrastructure, and property are vulnerable.
But a natural floodplain is supposed to get wet.
Seasonal inundation can refill depressions, connect fish to off-channel habitat, move organic material, deposit sediment, create shallow feeding areas, and reset plant communities. The same water that is destructive in a basement may be ecologically normal in a bottomland forest.
Flooding and flood damage are not the same thing. Flooding is a hydrologic process. Flood damage occurs when that process intersects with vulnerable homes, roads, crops, utilities, or other human uses. Good management has to deal with both realities at once.
That distinction matters because eliminating floodplain inundation everywhere would not be an ecological success. It would remove one of the processes that created these habitats in the first place. The practical question is where flooding can still occur with acceptable risk and where protection of people and infrastructure must take priority.
What wildlife actually gets from floodplain wetlands
Wetland articles often turn into long species lists. Lists are easy. The more useful question is what the habitat does.
Connected backwaters and inundated floodplains can provide shallow, low-velocity areas for feeding, refuge, spawning, or rearing. USGS research on a large river floodplain found evidence that several fish species used flooded terrestrial habitat for feeding or reproduction and concluded that lateral river-floodplain connectivity should be a management priority.[7]
Natural marshes, seasonally flooded forest, moist-soil units, shallow depressions, and flooded crops can all contribute different resources. Kentucky Fish & Wildlife describes Sloughs WMA as a mix of these habitats, including bald-cypress sloughs lined with buttonbush.[4]
Bottomland forests can connect river corridors across private and public land, giving birds and mammals cover, feeding areas, nesting habitat, and movement routes. At Patoka River NWR, the long-term restoration goal is a contiguous belt of bottomland forest along the river within the refuge boundary.[3]
Shallow temporary pools, wooded wetlands, marshes, and permanent backwaters do not function identically. Differences in duration, depth, vegetation, dissolved oxygen, and fish access can create very different breeding and feeding conditions.
None of this means every flood is beneficial to every species. Timing, depth, duration, water quality, temperature, and connectivity all matter. A wetland held too deep for too long can damage vegetation. A connection that helps native fish can also help invasive fish. Ecology rarely gives managers the courtesy of a one-direction answer.
Four places that show how the system works
No single property represents the whole Lower Ohio floodplain. Put several together, though, and a pattern appears. Water, forest, shallow wetlands, old channels, and public land repeat across state lines.
Hovey Lake Fish & Wildlife Area
Hovey Lake sits in the Ohio and Wabash River floodplains at Indiana’s southwestern corner. Indiana DNR describes approximately 7,404 acres that include a 1,400-acre oxbow lake, smaller sloughs and marshes, and extensive bottomland hardwood forest.[1]
The property makes the floodplain concept visible. The main lake is an old river feature, but the habitat value comes from the larger mix of water, woods, marshes, sloughs, and seasonal flooding. DNR notes that flooding can affect hunting access and trails, a reminder that ecological function and public use are often interacting on the same ground.
Patoka River National Wildlife Refuge
The Patoka refuge was established in 1994 to protect one of the few remaining expanses of bottomland forested wetlands in the Midwest and one of Indiana’s two intact floodplain forest systems. Its acquisition boundary covers 23,743 acres along about 30 miles of the Patoka River corridor.[2]
Within that boundary, the U.S. Fish & Wildlife Service reports 12,700 acres of wetlands. More than 1,000 acres of bottomland hardwoods have been planted as part of a long-term effort to restore frequently flooded agricultural fields and build a more continuous forest corridor.[3]
Sloughs Wildlife Management Area
Across the Ohio, Sloughs WMA contains a deliberately varied mix of waterfowl habitat: seasonally flooded grain, natural moist-soil vegetation, marsh, seasonally flooded bottomland forest, and natural sloughs with bald cypress and buttonbush.[4]
The connection to the Ohio is not theoretical. Kentucky Fish & Wildlife tells hunters to watch Ohio River stages because rising water can affect road access and determine whether boats are needed to reach some units.
Cache River & Cypress Creek wetlands
The Cache River State Natural Area occupies a floodplain carved long ago by glacial floodwater of the Ohio River. Illinois DNR describes cypress-tupelo swamp, floodplain forest, and ancient bald cypress within an 18,047-acre state natural area.[10]
Nearby Cypress Creek National Wildlife Refuge includes bottomland hardwood forest, cypress-tupelo swamp, herbaceous wetlands, and deep-water habitat. The larger Cache River-Cypress Creek wetland complex is recognized as a Ramsar Wetland of International Importance.[9]
These properties are managed by different agencies for different purposes. Yet the same ecological pieces keep appearing: low relief, periodic water, old channels, wet forest, shallow habitat, and the need to manage changing water conditions rather than a fixed shoreline.
How we changed the floodplain
The obvious version of this story is that people damaged wetlands. That is true in places, but it is incomplete enough to be misleading.
Floodplains are useful to people precisely because they are productive and close to water. Rich alluvial soils support agriculture. Rivers move freight. Flat ground attracts roads, industry, utilities, and towns. Levees protect communities and fields. Drainage makes wet land usable. Channel work can improve navigation and move water away from places where it creates repeated problems.
Those choices created real economic and safety benefits. They also changed the physical system.
In southwestern Indiana, USGS historical work describes broad marshes and forests on the Wabash and Ohio floodplains before extensive drainage, artificial channelization, and forest clearing.[8] Southern Illinois tells a similar but particularly visible story. Illinois DNR notes that the Cache River valley was shaped by an older Ohio River floodplain; later drainage, levees, channel changes, logging, and agriculture altered how water moved through that system.[10]
Once those changes accumulate, a wetland can remain on a map while functioning differently. A forest may still be standing but flood less often. A slough may hold water but lose its seasonal connection to the river. A levee may protect cropland while preventing fish from reaching former floodplain habitat. A drainage ditch may shorten the time water stays in a wetland. The habitat has not necessarily disappeared. Its operating system has changed.
Wetland acreage and wetland function are related, but they are not identical. Two sites of the same size can behave very differently depending on water source, depth, timing, duration, vegetation, soil, and connection to the surrounding river network.
Connectivity is the real issue
For much of the Lower Ohio region, the most useful question is not simply, “Is there a wetland here?” It is, “What is this wetland connected to, and when?”
Connectivity can be physical, hydrologic, and biological. Water may move between the river and floodplain. Fish may enter a backwater during high water. Nutrients and sediment may settle onto floodplain soils. Wildlife may move through a continuous forest corridor even when the ground is dry.
Break enough of those links and the floodplain becomes a collection of isolated pieces.
More connected
- Seasonal water can move into low floodplain areas.
- Fish and other aquatic organisms may gain temporary access.
- Sediment and nutrients can move between channel and floodplain.
- Wetland water levels respond more directly to river stage.
- Forested corridors may remain continuous along the river.
More disconnected
- Floodwater may be excluded or arrive less often.
- Off-channel habitat can become isolated from river fish.
- Wetland duration may depend more on rainfall, pumps, gates, or local drainage.
- Former floodplain can support agriculture or infrastructure more reliably.
- Ecological function shifts even if some wetland habitat remains.
Neither column is automatically “good” or “bad.” A levee protecting a community is doing an important job. A reconnected floodplain on public conservation land can also be doing an important job. The management challenge is deciding where each outcome makes sense and what tradeoffs come with it.
What restoration can actually mean
Wetland restoration is often pictured as digging a shallow basin, planting a few wetland species, and waiting for ducks to arrive. Sometimes that is part of the work. In a river floodplain, restoration can be much broader.
Patoka River NWR provides a good regional example. The refuge is restoring frequently flooded agricultural fields to bottomland hardwood forest, with more than 1,000 acres planted so far and a larger goal of building a contiguous forest corridor along the river.[3] That work is not creating a new river. It is changing land cover so the floodplain can support more of the structure and function associated with a bottomland forest.
Elsewhere, restoration may focus on water instead of trees. Managers might alter a drainage structure, reconnect an off-channel wetland, remove or modify a barrier where risk allows, restore shallow-water management, protect a tributary mouth, or improve fish passage. The Ohio River Basin Fish Habitat Partnership exists specifically to protect, restore, and enhance fish and mussel habitat throughout the basin.[11]
Restoration is not always about making a site look wetter. It is about restoring the processes, structure, and connections needed for the target ecosystem to function—and then checking whether the work actually did that.
The hard management questions are not going away
The Lower Ohio floodplain is not an empty conservation canvas. People live here. They farm it, hunt it, fish it, ship freight through it, build roads across it, draw drinking water from it, and depend on flood-control systems that exist for very good reasons.
That makes wetland management a negotiation among ecological goals, public safety, private property, economics, recreation, and long-term maintenance. The uncomfortable part is that several competing positions can be reasonable at the same time.
Where should rivers be allowed to reconnect?
Reconnection may improve habitat and floodplain function on conservation land or repeatedly flooded property, but it can be unacceptable beside homes, roads, utilities, or high-value agricultural infrastructure.
When is active water control better than “natural” hydrology?
Managed moist-soil units and water-control structures can produce valuable habitat. They also require staff, infrastructure, maintenance, and clear objectives. Natural fluctuation is not always possible on an altered site.
What happens when connectivity benefits unwanted species?
Connections that help native fish move can also move invasive species. More connectivity is not a universal answer. Managers have to know what organisms are likely to use the opening.
How much floodplain forest is enough?
A narrow strip may protect a bank but do little for species that need larger forest blocks. A broader corridor may provide more habitat value but require more land, more time, and more money.
What should success look like twenty years later?
A tree-planting project can be counted in acres on day one. Ecological success requires later questions about survival, forest composition, invasive plants, hydrology, wildlife use, and whether the corridor functions as intended.
Who carries the cost?
Public agencies, private landowners, hunters and anglers, taxpayers, conservation groups, farmers, industries, and communities can all have a financial stake. A plan that ignores costs usually does not become a durable plan.
This is why “save the wetlands” is not much of a management strategy. It identifies a value. It does not tell us which wetland, which process, which landowner, which water level, which species, which tradeoff, or which measure of success.
What this means for the Tri-State
Hovey Lake, the Patoka bottoms, Sloughs WMA, the Cache River wetlands, the Wabash floodplain, and hundreds of smaller sloughs, tributary mouths, farmed bottoms, wooded depressions, and backwaters are not interchangeable. They do not share one owner, one management plan, or even one type of hydrology.
But they are pieces of the same regional story.
The Lower Ohio Valley was shaped by rivers that moved, flooded, abandoned channels, deposited sediment, and repeatedly rearranged the boundary between land and water. We have spent generations making parts of that system more predictable for agriculture, transportation, communities, and industry. In many places that was necessary. In others, we now have an opportunity to decide how much river-floodplain function can be retained or restored.
That decision is bigger than protecting ducks, fish, cypress trees, or a scenic paddle route. It is about whether the remaining wetlands still operate as parts of a connected river system—or slowly become isolated remnants that happen to hold water.
The Lower Ohio River does not end at the edge of its channel. Where room remains, the floodplain is part of the river too. The future of the region’s wetlands will depend not only on how many acres we protect, but on which ecological connections we decide are still worth keeping.
Frequently asked questions
What is the difference between a wetland and a floodplain?
A floodplain is low land beside a river or stream that can be inundated when water rises. A wetland is defined by persistent or recurring wet conditions that influence soils, vegetation, and hydrology. Some floodplains contain extensive wetlands; other floodplain areas may be dry much of the time. The terms overlap, but they are not synonyms.
Is Hovey Lake connected to the Ohio River?
Hovey Lake is an oxbow lake within the Ohio and Wabash River floodplains. Its surrounding property includes sloughs, marshes, bottomland forest, and areas affected by flooding. The strength and timing of surface-water connections can change with river stage and local water conditions.
Why are bottomland hardwood forests important?
They provide forest habitat on flood-prone soils, connect river corridors, store organic material and sediment, and create feeding, nesting, cover, and movement opportunities for wildlife. Their ecological value depends on forest size, composition, hydrology, and connection to other habitat.
Are levees bad for wetlands?
Levees can reduce river-floodplain connectivity and change wetland hydrology, but they also protect communities, roads, farms, and infrastructure. Calling them simply good or bad misses the management question. The real issue is where flood protection is necessary and where reconnection can occur without unacceptable human risk.
Does more flooding always mean better wildlife habitat?
No. Wildlife responses depend on when flooding occurs, how deep it is, how long it lasts, water quality, temperature, vegetation, and which species can access the site. Flooding can create valuable habitat, but prolonged or poorly timed inundation can also damage vegetation or favor unwanted species.
Where can people see floodplain wetlands in the Tri-State?
Good public examples include Hovey Lake Fish & Wildlife Area and Patoka River National Wildlife Refuge in southwestern Indiana, Sloughs Wildlife Management Area in western Kentucky, and the Cache River State Natural Area/Cypress Creek National Wildlife Refuge complex in southern Illinois. Access changes with seasons, hunting regulations, and high water, so check the managing agency before visiting.
References
- Indiana Department of Natural Resources. (2026). Hovey Lake Fish & Wildlife Area. Indiana DNR Fish & Wildlife.
- U.S. Fish & Wildlife Service. (2026). Patoka River National Wildlife Refuge and Management Area: About Us. U.S. Fish & Wildlife Service.
- U.S. Fish & Wildlife Service. (2026). Patoka River National Wildlife Refuge and Management Area: Species. U.S. Fish & Wildlife Service.
- Kentucky Department of Fish & Wildlife Resources. (2026). Waterfowl quota hunts: Sloughs Wildlife Management Area. Kentucky Fish & Wildlife.
- Karstensen, K. A. (2008). Interior River Lowland Ecoregion Summary Report. U.S. Geological Survey Open-File Report 2008-1088. https://doi.org/10.3133/ofr20081088.
- U.S. Environmental Protection Agency. (2015). Connectivity of Streams and Wetlands to Downstream Waters: A Review and Synthesis of the Scientific Evidence. U.S. EPA.
- Barko, V. A., Herzog, D. P., & O’Connell, M. T. (2006). Response of fishes to floodplain connectivity during and following a 500-year flood event in the unimpounded Upper Mississippi River. Wetlands, 26(1), 244-257. U.S. Geological Survey publication record.
- Moore, D. W., Newell, W. L., Counts, R. C., Fraser, G. S., Fishbaugh, D. A., & Brandt, T. R. (2007). Surficial geologic map of the West Franklin quadrangle, Vanderburgh and Posey Counties, Indiana, and Henderson County, Kentucky. U.S. Geological Survey Scientific Investigations Map 2967. U.S. Geological Survey.
- U.S. Fish & Wildlife Service. (2026). Cypress Creek National Wildlife Refuge: About Us. U.S. Fish & Wildlife Service.
- Illinois Department of Natural Resources. (2026). Cache River State Natural Area. Illinois DNR.
- U.S. Fish & Wildlife Service. (2026). Ohio River Basin Fish Habitat Partnership. U.S. Fish & Wildlife Service.
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